Contents and Abstracts of Journal of Mechanical Engineering ISSN 0577-6686, CN 11-2187/TH*

Vol. 46, No. 1, 2010

* Few of the contents and abstracts shown here may be different with the ones published in Journal of Mechanical Engineering

Structural Design and Hydrodynamics Analysis of a Self-reconfigurable Propeller

DING Xilun1WANG Zhengrong1,2ZHANG Wuxiang1

(1. Robotics Institute, Beihang University, Beijing 100083, China;2. Navy Logistic Technology and Equipment Institute of PLA,Beijing 100072, China)

A novel design concept is proposed to improve the efficiency of traditional boat propellers, and a propeller with self-reconfigurable structure is designed, its blades can open and close automatically to satisfy the need of water propelling. The mechanism of this new-style propeller is analyzed and the configurations in different working states are studied,and three of which are presented. Assuming that the propeller rotates at an even speed in idealized flood, the trajectory of a certain point on the blade is obtained according to the theory of flood dynamics, and the motion analysis of the propeller blade mechanism is performed. According to the characteristics and working principle of this new propeller system, the induced velocity, thrust and torque are derived on the basis of the lifting line theory and blade elements theory, the hydrodynamic performance analysis model is built and simulated. Efficiency of the propeller with self-reconfigurable structure is calculated. A comparative study between this new style propeller and the traditional propellers shows the superiority of the former.

Self-reconfigurable mechanism Structural design Propeller Hydrodynamics

PP. 1-9

Adaptive Interactive PID Supervisory Control of the Macro-micro Parallel Manipulator

DUAN Xuechao QIU Yuanying DUAN Baoyan CHEN Guangda BAO Hong MI Jianwei

(Key Laboratory of Electronic Equipment Structure of Ministry of Education, Xidian University, Xi’an 710071, China)Abstract:The supporting, orientating and trajectory tracking mechanism of the five hundred meter aperture spherical radio telescope (FAST)consists of a macro-micro parallel manipulator system. The macro parallel manipulator (feed cabin) driven by the large span flexible cables assures the large reachable workspace, while the micro parallel manipulator(Stewart platform) driven by the delicate electrical cylinders realizes the precision of the end-effector and expands the servo bandwidth. In order to decrease the impact of the flexibility of the macro parallel manipulator on the precision of the end-effector, a decoupled tracking and prediction algorithm based on the principle of parallel mechanisms is presented. This algorithm is used to predicate the future position and orientation of the feed cabin. Then the adaptive interactive PID controller, which utilizes the adaptive interactive algorithm to adjust the parameters of conventional PID controller, is devised as the supervisory controller in the joint space of the Stewart platform. The supervisory controller generates the control commands in the upper level of the electrical cylinders. Besides, in the lower level of the electrical cylinders, the digital servo filters with feedforward are employed to track the desired trajectory accurately. The experiments of the FAST50 m field model validate the effectiveness of the adaptive PID supervisory controller, accompanied with the motion predication of the feed cabin. The macro-micro parallel manipulator system can obtain the satisfactory positioning and orientating precision with the desired tracking velocity.

Key words:Radio telescope Macro-micro parallel manipulator Stewart platform Adaptive interaction Supervisory control

PP. 10-17

Theoretic Model and Position Solution of a Cable Mesh Mechanism

GUO Yongwei WANG Qiming

(National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China)

Abstract:The cable mesh mechanism is a kind of flexible, parallel motion mechanism array. The motion theoretical analysis is important for the complex and coupled movement. The theoretical model of the cable mesh mechanism is setup via undigraph, and expressed in computer via adjacency list. The cable is simplified and regarded as a linear spring-sliding pair. Based on force density method, the balance equations of the active node are built, and extended to the whole cable mesh motion mechanism. The problem how to solve the balance equations is discussed,and the positional relationship between actuator ends and active nodes of the cable mesh mechanism is deduced and expressed in iterative equations.Then a position analysis method is built. By programming, the cable mesh motion mechanism of the 30 m model of the five-hundred-meter aperture spherical telescope (FAST) is modeled, and its motion is simulated. The results are same as that simulated in Adams software. The position analysis method is verified. It can be used in the real-time control arithmetic of the FAST active reflector, and can be used in precise adjustment or control of the reflector shape for other large cable mesh antennas and space deployable reflectors as well.

Key words:Cable mesh Mechanism Force density method Data structure Decoupling Large radio telescope

PP. 18-23

New Approach for Analyzing the Stiffness of 3-RPS Parallel Manipulator

HU Bo LU Yi

(College of Mechanical Engineering, Yanshan University,Qinhuangdao 066004, China)

Abstract:For lower mobility parallel manipulators (PMs), the constrained forces/torques appear because the structure constraint exists. The constrained forces/torques must be considered in analyzing the stiffness for PMs because the constrained forces/torques can produce elastic deformation and affect the precision of PM. The stiffness of a traditional parallel manipulator 3-RPS is analyzed to illustrate this method. First, the constrained forces are analyzed on the basis of the observation method.Second, the 6×6 Jacobian matrix is established, and the statics model is established by applying the principle of virtual work. Finally, the deformation of the PM is analyzed with the active forces and the constrained forces considered. The stiffness of 3-RPS PM is analyzed by converting the 3-DOF PM into a 6-DOF PM free from constrained forces/torques by setting virtual P joints along the direction of constrained forces. This method provides some new points of view for lower mobility PMs.

Key words:Statics Jacobian matrix Stiffness PP. 24-29

Hybrid Serial-parallel 6R Robot Made of RGRR-Ι

JIANG Ming1,2YI Hong1LI Luyang2NI Zhonghua1ZHOU Jianhua2

(1. College of Mechanical Engineering, Southeast University,Nanjing 210036, China;2. College of Mechanical Engineering, Yangzhou University,Yangzhou 225001, China)

Abstract:Since a new 2-DOF rotation parallel mechanism (RGRR-Ⅰ )has the advantages of less moving parts and large workspace, hybrid serial-parallel 6R robot is invented by using threemechanisms in order to realize high stiffness as well as large workspace and compact structure. Replacing position analysis of hybrid serial-parallel mechanisms with position analysis of each less-freedom parallel machine and serial analysis of moving coordinate parameters by establishing the relation between moving coordinate parameters of less-freedom parallel machines and input parameters of machines, a new method of hybrid serial-parallel mechanisms position analysis is proposed in order to reduce the difficulty of position analysis and get result easily. It is very useful for kinematics analysis of other hybrid serial-parallel mechanisms.

Key words:Hybrid serial-parallel mechanisms Parallel mechanisms Workspace Rotation Degree of freedom

PP. 30-36

Simulation on the Control Strategy of a New Super-mild Hybrid Transmission System

SUN Dongye1ZHUANG Jianbing2QIN Datong1LIU Zhenjun1

(1. The State Key Laboratory of Mechanical Transmission,Chongqing University, Chongqing 400044, China;2. Xiamen Xiagong Xinyu Machinery Co., Ltd.,Xiamen 361004, China)

Abstract:In order to reduce production cost, improve control effect of saving fuel and reducing emission, a new super-mild hybrid transmission system is developed to over the limitation of the existing mild hybrid electric vehicle (HEV) which has not the working condition as the pure electric drive. The new one is based on continuously variable transmission(CVT) with reflux power, which features wide speed ratio range, high transmission efficiency and big loading ability. Through adoption of the new transmission mode and match control strategy, the match design theory and control method of hybrid transmission system based on large speed range are researched. The test results show that the super-mild HEV saves fuel by 13.02%, in which 1.88% is contributed by the continuously variable transmission (CVT) with reflux power.

Key words:Hybrid transmission Continuously variable transmission Control strategy Simulation analysis

PP. 37-42

Correction of Tooth Flank Errors of Spiral Bevel Gear Based on Proportional Change Parameters

WANG Zhiyong ZENG Tao

(College of Mechanical and Electrical Engineering,Central South University, Changsha 410075, China)

Abstract:A method for correcting tooth flank errors of spiral bevel gears is investigated. Based on the mathematical model of tooth flanks, the tooth surface is discretized and then the radius vector and normal vector of discrete points is presented. The expression of tooth flank errors of modified tooth surface relative to theoretical one is established. According to the measuring data of tooth flank errors of real tooth surface, the difference surface is deduced. On the basis of setting up the relationship between the characteristic parameters of difference surface and proportional change parameters obtained from machine tool setting calculation, an error correction method based on proportional change parameters and the values of tooth flank errors of real tooth surface is proposed. By applying optimization algorithm, the coefficients of proportional change parameters are computed and then the correction values of machine tool settings are obtained. The tooth flank errors can be corrected by utilizing modified machine tool settings. The correction method of tooth flank errors is validated through practical tooth grinding and measurement of tooth flank.

Key words:Spiral bevel gear Tooth flank errors Proportional change parameters Error correction

PP. 43-47

Numerical Simulation of the Hydrodynamics of Fishlike Robot Swimming Based on Converged Speed

XIA Dan LIU Junkao CHEN Weishan HAN Luhui

(State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin 150080, China)

Abstract:The speed convergence algorithm is applied in the numerical simulation of a fishlike robot swimming straight forward. For an initial value given arbitrarily, the swimming speed is dynamically modified to converge to the steady value by verifying the thrust and drag forces during the swimming process. Numerical simulation of the hydrodynamic performance of the fishlike robot is carried out on the basis of the converged speed in order to reveal its propulsive mechanism and flow field structure. The results show that the steady-state swimming speed can be predicted effectively by using the speed convergence algorithm, while the thrust force, power consumption and propulsive efficiency can be obtained through varying the swing frequency and the maximum swing amplitude. The effects of positive pressure gradient and the adverse pressure gradient are clearly reflected in the 3-dimensional flow field structure around the robot. The numerical findings are of great significance to predicting the swimming speed, revealing the propulsive mechanism, and designing the motion parameters of fishlike robot.

Key words:Fishlike robot Speed convergence algorithm Converged speed Propulsive mechanism Flow field structure

PP. 48-54

Mobility Bifurcation of Two 1R3T Parallel Mechanisms Based on Lie Group

CHEN Qiaohong LI Qinchuan WU Chuanyu HU Xudong

(Provincial Key Laboratory of Modern Textile Machinery,Zhejiang Sci-Tech University, Hangzhou 310018, China)

Abstract:Mobility bifurcation of 1R3T (R—rotational, T—translational)parallel mechanisms is studied by applying Lie group theory. Some theoretical fundamentals necessary for application of Lie group theory to mobility analysis of parallel mechanisms are briefly reviewed. Mobility analysis of the 2-xPyRyRxRxR/yPxRxRyRyR and 2-xPyRuPxRxR/yPxRvPyRyR parallel mechanisms is performed. It is proved that the two parallel mechanisms have mobility bifurcation with displacement set of the moving platform being {X(x)}∪{X(y)}. Further, it is obtained that the limb displacement manifold of the 1R3T parallel mechanism with mobility bifurcation is {G(x)}{G(y)} or {X(x)}{R(N, y)}. The structural geometrical conditions of the 1R3T parallel mechanism with mobility bifurcation are also presented. When the moving platform is parallel to the base, the parallel mechanism is in a singular configuration and the moving platform has five instantaneous degrees of freedom. The mobility bifurcation happening in this singular configuration requires five actuators to control the motion of the moving platform.

Key words:Parallel mechanism Lie group Mobility

PP. 55-61

Dynamic Behavior for Planetary Geared System with Plastic Gear

DUAN Fuhai1HU Qingchun2XIE Cunxi2

(1. Electromechanical Engineering & Automation Department,Fujian University of Technology, Fuzhou 350108, China;2. School of Mechanical and Automotive Engineering,South China University of Technology, Guangzhou 510640, China)

Abstract:The key issue is how substituting plastic gears for steel ones affects planetary gear dynamic behavior. A torsional dynamic model of planetary gears is presented with time-varying meshing stiffness, damping,error excitation and gear compliance considered. The vibration teat rig for planetary geared system is also constructed. The dynamic behavior of the planetary geared systems composed of S(steel)/N(plastic)/S(steel), SSS,SSN and NSS (sun/planet/ring gear) are investigated. Numerical and experimental results demonstrate that plastic gears can dramatically change the dynamic behavior of planetary geared systems. The numerical results on the planetary geared system indicate that plastic gears can reduce dynamic loads on sun-planet and ring-planet gear mesh markedly.The experimental results also show that substituting plastic gears for steel ones can effectively reduce the high and low frequency vibrations for planetary geared systems.

Key words:Plastic gear Planetary gear Dynamic behavior Compound mode

PP. 62-67

Dynamic Modeling and Robust-adaptive Iterative Learning Control of 3-RRR Spherical Parallel Mechanism

WANG Yueling1,2JIN Zhenlin1LI Yanbiao1

(1. College of Mechanical Engineering, Yanshan University,Qinhuangdao 066004, China;2. Key Laboratory of Industrial Computer Control Engineering of Hebei Province, Yanshan University, Qinhuangdao 066004, China)

Abstract:A dynamic model based on attitude parameters of moving platform for a 3-RRR spherical parallel robot is developed by using Lagrange method. Further, a dynamic model with parameter uncertainties is developed considering the parameters uncertainties caused by tiny changes such as approximately computing in linear density, thickness, and mechanism abrasion during working process. Aiming at its characteristic of acting repeatedly in vibration measuring and parameter uncertainties, a robust-adaptive iterative learning controller (ILC) is designed for this mechanism, and its stability is proved. The adaptive algorithm, which is powerful in leaning unknown constants, is used to compensate the uncertain parts of dynamics model, and the iterative learning algorithm is used to track the desired path without errors. Because of the utilization of certain information of dynamics model, the Lipschitz condition necessary for most unknown systems during iterative learning control is avoidable.The simulation results indicate that this robot can accurately track the desired path repeatedly.

Key words:3-RRR spherical parallel robot Dynamics Lagrange method Iterative learning control

PP. 68-73

Bond Graph Method for the Dynamic Similarity Analysis of Complex Electromechanical System

WANG Ailun1,2LIU Yun1,2

(1. College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China;2. Key Laboratory of Modern Complex Equipment Design and Extreme Manufacturing of Ministry of Education,Central South University, Changsha 410083, China)

Abstract:The existing similitude methods can only be applied to the dynamic similarity analysis of elements (or components) with single-energy domain, and there are many difficulties when they are utilized to study the dynamic similarity of complex electromechanical system with multi-energy domains. To solve this problem, the prerequisite condition for the similarity of bond graph of system is explored and the dynamic similarity conditions for the elements of bond graph are derived on the basis of bond graph which is an effective tool for modeling of system with multi-energy domains. The system modal similarity is analyzed and studied according to the mode analysis theory based on bond graph. The similarity relations of major modal parameters such as frequency and vibration mode are established. Thus, the bond graph method for dynamic similarity analysis of complex electromechanical system is presented. The similarity requirements for the system can be easily derived without the physical equations, and the dynamic model test of system with multi-energy domains can be achieved by a simple single-domain model system when the new method proposed is utilized in the dynamic similarity analysis, which provides new methods and ideas for the research on dynamic similarity of complex electromechanical system. The example provided shows that the similarity conditions can be derived efficiently and conveniently when the method is utilized to instruct the dynamic similarity design and model test of complex electromechanical system.

Key words:Complex electromechanical system Dynamics Similarity analysis Bond graph Model test

PP. 74-78

Separation and Extraction of Electromechanical Equipment Compound Faults Using Lifting Multiwavelets

YUAN Jing HE Zhengjia ZI Yanyang

(State Key Laboratory for Manufacturing and Systems Engineering,Xi’an Jiaotong University, Xi’an 710049, China)

Abstract:Compound faults of electromechanical equipment always occur simultaneously and in a cascading way. Based on signal matching,multiwavelets with good properties have several scaling functions and wavelet functions. Therefore, they could better match various features of compound faults, and separate and extract compound features at one time.The construction of multiwavelets based on lift frame does not depend on the Fourier transform, and the algorithm is simple and fast. Hence,multiwavelet transforms via lift frame like the second wavelet transforms are studied. Based on Hermite spline interpolation, the new multiwavelets with short support, biorthogonality, symmetry and fourth approximate order are designed, and the corresponding preprocessing algorithm is given. Aimed at the problem of compound faults, posttreatment procedure is modified and decoupled features are clearly presented in different channels of analysis results of multiwavelets. The proposed method is applied to compound faults diagnosis for bearing test bench and traveling unit of electric locomotive. The results show that this method can effectively separate and extract the features of bearing inner-race fault and shaft anomalous bending, and successfully decouple the bearing outer-race defect and roller defect of the locomotive.

Key words:Multiwavelets Lifting Compound faults Monitoring and diagnosis

PP. 79-85

Analysis of Harmonic Oscillation Synchronization for the Single-mass Nonlinear System under Harmonic Wave Sharp Resonance Condition

LI Xiaohao LIU Jie LIU Jintao

(School of Mechanical Engineering and Automation,Northeastern University, Shenyang 110004, China)

Abstract:Based on the dynamic model of single mass nonlinear system,the necessary conditions of harmonic oscillation synchronization motion are deduced, under harmonic wave sharp resonance (main resonant frequency ratio z= 0.9 5 ～1.05) condition and dual vibration exciters rotating in opposite direction are moving at the balance singular point.Using the numerical simulation, the valid of the harmonic oscillation synchronization conditions are investigated under different initial conditions. The process of theoretical derivation, consequence of simulation tests and actual tests data indicate that if the systemic characteristic parameter remain constant, the vibration synchronization phenomena of single-mass nonlinear system under harmonic wave sharp resonance condition have direct relationship with the harmonic wave sharp resonance order p/q, and harmonic oscillation synchronization order n/m.But the harmonic oscillation synchronization phenomena of the dual vibration exciters only occur at a certain radio of p/q and n/m which conform to the specific mechanical characteristic conditions of nonlinear system. And they also indicate that the realization of system main resonance synchronization is far easier than system harmonic oscillation synchronization. This research provides theoretical support and test basis for further exploitation of efficient and energy-saving nonlinear sharp resonance shaker.

Key words:Single-mass Nonlinear Harmonic wave sharp resonance Harmonic oscillation synchronization

PP. 86-91

Dynamic Characteristic Parameters of Linear Guideway Joint with Ball Screw

JIANG Shuyun ZHU Shulong

(School of Mechanical Engineering, Southeast University,Nanjing 211189, China)

Abstract:A dynamic model of linear guideway joint with ball screw is built by means of the linear stiffness of linear rolling guideway and the axial stiffness of ball screw and angular contact ball bearing, which can be calculated by using the Hertz Contact Theory of elastic mechanics, and related computer program for calculating the contact stiffness is developed.A vertical machining centre is selected as an example, the effect of cutting load on the dynamic stiffness of joint part is analyzed, and the dynamic characteristics of the entire machine tool with the joint stiffness considered are also discussed on the basis of finite element method. The analytical results show that it can not only overcome the shortcoming of the conventional method in without considering the effect of ball screw pair,but also appear clarity in physical concept and simplification in computation.

Key words:Joint of linear guideway Ball screw Dynamic stiffness characteristic parameters Hertz contact theory

PP. 92-99

Difference Spectrum Theory of Singular Value and Its Application to the Fault Diagnosis of Headstock of Lathe

ZHAO Xuezhi YE Bangyan CHEN Tongjian

(School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, China)

Abstract:It’s proved that signal can be decomposed into the linear sum of a series of components by singular value decomposition (SVD) when Hankel matrix is used. In order to determine the proper number of useful components, the concept of difference spectrum of singular value is put forward. Difference spectrum can effectively reflect the difference of singular values of the useful components and noise ones, and the number of useful components can be determined according to the peak position in the difference spectrum. The research results show that if the maximum peak is in the first coordinate, it means that a major direct current component exists in the signal and under this circumstance the number of useful components will be determined by the second maximum peak position, otherwise the number of useful component is determined by the maximum peak position. The influence of Hankel matrix structure on noise reduction effect of SVD is studied by dint of difference spectrum and it’s pointed out that there exits a parabolic symmetry relationship between matrix column and noise erasing amount. On these bases this method is applied to the processing of turning force signal and the modulated signal caused by the gear vibration in the headstock is isolated successfully, furthermore the fault gear is located reliably according to this isolated signal.

Key words:Singular value decomposition Difference spectrum of singular value Peak position Denoise Turning force signal

PP. 100-108

Finite Element Approach for Analyzing Continua with Damp under Harmonic Loads from the Base

LIU Jiantao1DU Pingan1HUANG Mingjing2XIAO Yaobing2

(1. College of Mechanical and Electronic Engineering,University of Electronic Science and Technology of China,Chengdu 610054, China;2. China Gas Turbine Establishment, Jiangyou 621703, China)

Abstract:There are lots of restrictions to numerical simulation of continua vibrations from the base, including rigid-body motion, constrains,loading mode, stability of numerical algorithm and so on. By theoretical deduction and FEM calculation of the structural response under harmonic vibration of the base, a new effective approach called static inertia method is proposed. Based on the equivalent form of base load, general FEM software and self-developed data processing program, the new method transforms the original problem into an ordinary harmonic vibration problem with fixed base. Both of experimental and numerical results with the probe for detecting the temperatures inside turboprop indicate that the static inertia method is an effective method with simple implementation and accurate response results. It overcomes the restrictions of existing methods and provides a new approach to solving the problems such as harmonic vibration, flush and anharmonic vibration from the base.

Key words:Finite element Harmonic vibration Base excitation Response history Equivalent load

PP. 109-114

Self-excited Vibration in a Pneumatic Pilot-operated Solenoid Valve

YE Qifang YAN Shijie CHEN Jiangping CHEN Zhijiu

(School of Mechanical Engineering, Shanghai Jiao Tong University,Shanghai 200240, China)

Abstract:Self-excited vibration in solenoid valve is one of the noise sources and it will cause unstable working of pneumatic system. In order to study self-excited vibration in solenoid valve under different working conditions, the vibration is studied numerically and experimentally. A dynamic model coupling vibration of solenoid valve with fluid flow in valve is developed. The model is validated by experimental results.Working state of the system, effects of structural parameters are discussed.A review of the numerical results obtained indicates that for low working pressure and small working flow rate, the equilibrium point of the system is unstable, “soft self-excited vibration” occurs due to infinitesimal disturbances. The solenoid valve undergoes soft self-excited vibration,hard self-excited vibration, with the increase of supply pressure or supply flow rate leading to stable working. Increase in dband decrease in da, z0, α will improve anti-disturbance capacity and enlarge stable working region of the solenoid valve.

Key words:Dynamic model Self-excited vibration Solenoid valve

PP. 115-121

Method for Asymmetric Distributed Loads on Curving Areas in Products Simulation Analysis

LIN Xiaoxia ZHANG Shuyou CHEN Jing XUE Yang

(The State Key Lab of Fluid Power Transmission and Control,Zhejiang University, Hangzhou 310027, China)

Abstract:In order to solve the problem of asymmetric distributed loads on curving areas, and improve the efficiency and quality in complicated products finite element method (FEM) analysis, the method for asymmetric distributed loads on curving areas based on the eigenfunction distribution of FEM is put forward. The basic concept of loading eigenfunction is presented. The loading of asymmetric distributed loads on unrestricted curving areas and cylindrical areas is researched. The curving areas are discretized into small-unit grids. The load on the grids (or nodes)of unrestricted curving areas can be calculated automatically according to the eigenfunction of load distribution and the shape of curving areas. The method is proved to be steady and reliable through the experiment of putting the asymmetric distributed loads on the impeller curving areas.The loading of asymmetric distributed loads on unrestricted curving areas and cylindrical areas can be implemented faster by using this method, and the FEM analysis of uneven surface load in complicated products can be solved effectively.

Key words:Eigenfunction Unrestricted curving areas Dispersion to load Finite element method Simulation analysis

PP. 122-127

Methodology of Designing for Time-varying Performance of Complex Products

MENG Xianghui XIE Youbai DAI Xudong

(School of Mechanical Engineering, Shanghai Jiao Tong University,Shanghai 200240, China)

Abstract:The methodology of designing for time-varying performance of products is analyzed to overcome the system degradation of products during running. For complex mechanical products, the following three key problems are presented to be solved. First, a benchmark of working condition or system degradation process should be set up to evaluate time-varying performance of different design schemes. Second, the coupling among different disciplines should be analyzed to simulate the transient system behaviors of products. Third, the degradation process of system structure and performance should be predicted and analyzed to provide information for the design decision. The case study on the internal combustion engine demonstrates that the system wear or other system degradation phenomena influence the system performance obviously. So the key factors related with performance should be found out and optimized on the basis of system time-varying performance degradation analysis. The research indicates that the time-varying performance is vital to complex products and the methodology presented in this paper will lay a foundation for improving the time-varying performance of products.

Key words:Time-varying performance System degradation Transient system behaviors Complex products

PP. 128-133

Experiments on Reuse-oriented Disassembly of Components from Printed Circuit Boards

YANG Jiping1,2XIANG Dong1CHENG Yang1GAO Peng1DUAN Guanghong1FENG Jian2

(1. Department of Precision Instruments and Mechanology,Tsinghua University, Beijing 100084, China;2. Department of Oil Supply Engineering, Logistic Engineering University, Chongqing 400016, China)

Abstract:In order to realize reuse-oriented disassembly of components from printed circuit boards(PCB) and develop PCB disassembly process and apparatus, it is necessary to analyze and evaluate the influences of various parameters on reusability and disassembly efficiency of components. Mainboards of scraped computers are taken as samples,experiments are performed with three kinds of removal forces and four kinds of heating parameters on a pilot disassembly apparatus under the conditions of hot air heating, and the disassembly efficiency of components is analyzed and the disassembled components are evaluated for reuse. The experiments show that it has a high components disassembly ratio (CDR) for SMDs and THDs with unclinched pins under three kinds of removal forces (contact impact, non-contact impact and vibration). To improve the components disassembly ratio of waste PCBs,the disassembly ratio of slot and connectors should be concentrated on. To improve the reusability ratio of disassembled components, the reusability of IC chips with more than 100 pins should be regarded mainly. In addition, the optimal level range of heating parameters is analyzed with the purpose of better disassembly ratio. The results also show that small impact potential energy is favorable to a high reusability. These experiments provide the basis for determining the reuse-oriented disassembly process of components and also for developing the disassembly apparatus.

Key words:Waste printed circuit board Disassembly process Reuse Resource recycling

PP. 134-139

Multi-objective Optimization Design of Heavy Forge Framed Hydraulic Press Driven by Stiffness and Mass

LI Yancong1ZHANG Lianhong1LIU Zhanwen1WEI Wei1LI Sen2

(1. College of Mechanical Engineering, Tianjin University,Tianjin 300072, China;2. Tianjin Tianduan Press Co., Ltd, Tianjin 300142, China)

Abstract:In order to satisfy the performance requirement of high stiffness and light weight of the NC isothermal hydraulic press, a design method of multi-objective optimization driven by stiffness and mass is proposed.Through analyzing the structure of 98 MN hydraulic press, key factors affecting the stiffness and mass are extracted. Data of relationship between stiffness / strength and key factors are obtained by orthogonal experiment in ABAQUS. The mathematical models of stiffness of upper beam and lower beam and strength of main components are constructed by use of first order response surface modeling method. Validity of these models is verified by analysis of variance. Mathematical models of mass of complete hydraulic press are established. The goal of high stiffness and light weight is reached by using the multi-objective genetic algorithms optimization method. The Pareto optimal solution set is obtained.Through optimization, the stiffness of 98 MN hydraulic press is increased by 5% and its mass is decreased by 10% in comparison to the original design.

Key words:Hydraulic press High stiffness Light weight Multi-objective optimization Orthogonal experiment Genetic optimal algorithms of non-dominate-solution order

PP. 140-146

Template Based Interference Detection Technology of Large Components Assembly

ZHANG Xu1JIA Zhixin1ZHANG Xuechang1KE Yinglin2

(1. Ningbo Institute of Technology, Zhejiang University,Ningbo 315100, China;2. College of Mechanical and Energy Engineering,Zhejiang University, Hangzhou 310027, China)

Abstract:In order to make quantitative analysis of the interference situation during insertion and fit of large components, a template based interference detection technology is proposed. The template is customized according to the CAD model of insertion and fit characteristics. After match with scanning data, the template is taken as the reconstruction model to take part in the interference analysis. The insertion characteristic is discretized into a series of parallel sections perpendicular to the assembling direction, and the penetration depth, clearance and interference demarcation line of each section relative to the fit characteristic in the process of motion is calculated. The integration of interference situations of all sections constitutes the interference situation of insertion and fit characteristics. This method simplifies the 3D intersection problem to a 2D one, and not only can calculate quantitatively the penetration depth and clearance but also can give the interference distribution of assembly parts.Based on this, the handling of follow-up assembly is guided quantitatively.Finally, through the simulated interference detection and analysis of a pair of insertion and fit characteristics, the interference results including maximum interference quantity and distribution are. given, which verifies the feasibility of the proposed interference detection technology.

Key words:Template Point cloud Interference detection Interference distribution

PP. 147-153

Analysis of Engineering Change Impacts Based on Design Structure Matrix

TANG Dunbing XU Ronghua TANG Jicheng HE Rui

(College of Mechanical and Electrical Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 210016, China)

Abstract:Product development involves massive engineering changes.Engineering changes will prolong the time of product development and increase product cost more or less. The ability to manage engineering changes efficiently reflects the agility of an enterprise. Up to date there is a lack of effective methods to analyze and evaluate the impacts of the engineering change owing to the complexity of change propagation. Based on design structure matrix, an analytical model is set up, and the concrete method for analyzing direct and indirect engineering change impacts is proposed. Considering the probability and risk of engineering change, a mathematical model is presented to predict the comprehensive impact of engineering change. A motorcycle engine case study validates the feasibility of the proposed model.

Key words:Engineering change Design structure matrix Change propagation Engineering change impacts

PP. 154-161

Hydrodynamic Performance Analysis and Optimization Design of Mechatronic Ducted Propeller with CFD

YANG Qiongfang1WANG Yongsheng1FAN Lu2

(1. College of Ship and Power Engineering, Naval University of Engineering, Wuhan 430033, China;2. School of Transportation, Wuhan University of Technology,Wuhan 430063, China)

Abstract:Computational fluid dynamics (CFD) is applied in the whole process of hydrodynamic performance analysis and optimization design of a mechatronic ducted propeller. The open water characteristics of a ducted propulsor with a stator behind its rotor are calculated, hydrodynamic force coefficients show good agreement with the experiment data, which indicates the validity of CFD method. The hydrodynamic performances of the preliminary design mechatronic ducted propeller are calculated with the same CFD method, including putting forward the major geometrical dimensions of the shrouded duct in hydrodynamics terms by simulation,and validating the calculated results by changing the mesh type and distribution. An optimization design, which improves the tip flow and enhances the open water efficiency, can be achieved by shortening and thickening the ring and changing the blade geometry correspondingly after analyzing the effect of ring without winding to the flow pattern of tip clearance and hydrodynamics of ducted propeller, as to the component duct or propeller itself and to the whole geometry. Numerical simulation is conducted to the secondary design ducted propeller under design and off-design conditions. The calculated pressure distribution around the ring is compared with that of the preliminary one, and comparison of the propulsion performance is also completed with the second one to the first one, and to the experiment simultaneously. It is shown that the use of CFD to the preliminary design and performance analysis of the duct propulsor is effective. With a large radial distance of the clearance, the pressure reduction in the clearance and the range of local stagnation flow region will be large also. The longer the ring in the axial direction is, the more vortexes in the turnaround tip flow will be. The existence of the ring is beneficial to axial force of the duct, but not to the blade, as it makes the efficiency of the ducted propeller lower. The thrust coefficient of the redesigned ducted propeller is higher than that of the first one, moreover,the torque coefficient is lower, and the open water efficiency is higher,thus showing the correctness of the improvement.

Key words:Ship Ducted propulsor Mechatronic ducted propeller Numerical simulation Performance analysis Optimization design

PP. 162-168

Design and Experimental Research of a New Type of Piezoelectric Rotary Actuator

LIU Xiangfeng LIU Dawei GAO Zhi LIU Ying QIU Tian

(The State Key Laboratory of Tribology, Tsinghua University,Beijing 100084, China)

Abstract:A new type of piezoelectric rotary actuator is designed and developed to simplify the structure and improve the energy efficiency. The actuator adopts the piezoelectric bimorph as the prime driver. With the movement transformer, the bending deflection is converted into torsion motion, then through the dual-clutch coupling transmission, the torsion is converted into rotation. The finite element simulation analysis method is used to carry out in-depth research of the physical property of actuator,and the key parameters of the actuator are measured. The research shows that the speed of the developed piezoelectric rotary actuator is in linear relation with the signal frequency and the voltage applied to the piezoelectric bimorph, and the actuator has certain load carrying capability.By comparing experiment data with the finite element simulation results,the error origins are analyzed and founded. This provides the reference for further optimization design of the actuator. The investigation proves the feasibility of the design method of piezoelectric bimorph rotary actuator.The developed actuator is simple in structure, small in volume. It is suitable for use in the micro drive field as the piezoelectric rotary actuator.

Key words:Piezoelectric bimorph Rotary actuator Dual-clutch coupling

PP. 169-174

Optimal Selection of Technics Routine Based on Aircraft Automatic Join-assembly

YU Fengjie KE Yinglin FANG Qiang

(College of Mechanical and Energy Engineering, Zhejiang University,Hangzhou 310027, China)

Abstract:To satisfy the requirements of technological comparison and evaluation during aircraft automatic join-assembly, a methodology of optimal selection for certain type airplane is proposed. Calculation procedures as well as simplified models for effectiveness function, cost function and effectiveness-cost ratio are described by utilizing the assembly examples in database as the data source. Based on nonparametric statistical method, independence test of 2-way contingency table is introduced to analyze the correlation between technological routine and technological performance. Then optimal selection and solution of technological routine is realized through Wilcoxon rank-sum test. To reduce the influence of random factors, fuzz cluster procedure is introduced. Thus optimal selection and solution of technology of typical example sets is realized. The application instance indicates that statistical conclusions can be deduced from historical data by using this method and the objective is to select a superior assembly technology, obtain assembly knowledge, control assembly cost, and improve the accuracy and efficiency of aircraft assembly.

Key words:Aircraft Join-assembly Optimal selection of technology Effectiveness function Cost function Nonparametric statistical method

PP. 175-181

Micromachining Processing of 3D Micro Tensile Specimens Based on Inductively Coupled Plasma Etching

ZHANG Duanqin CHU Jinkui HOU Zhiwu WANG Liding

(Key Laboratory for Precision & Non-traditional Machining of Ministry of Education, Dalian University of Technology,Dalian 116023, China)

Abstract:Based on the mechanism of inductively coupled plasma (ICP)etching, the micromachining processing of 3D micro tensile beams is researched in the light of the structure characteristics of the thermal silicon dioxide micro-tensile beams and with the purpose of solving the main problems in the processing. The influences of ICP etching process parameters on etching quality, including micro loading effect and aspect ratio effect in existence, are presented. The micromachining processing of the beams is introduced in detail. The pivotal procedure is double-masks-twice-ICP etching to form stair-opening structures and to double-masks-twice-ICP etching to form stair-opening structures and to obtain the free-standing thermal silicon dioxide beams on the surface of silicon. Using the high selectivity of single crystal silicon in ICP etching,the processing method is applicable in the fabrication of micro tensile beams with various films.

Key words:Inductively coupled plasma etching Stair-opening structure Thermal silicon dioxide film Micro tensile beams

PP. 182-186

Calculating Transient Temperature Distribution of Single-coated Tool in High Speed Cutting

ZHANG Shijun LIU Zhanqiang LIU Jigang

(School of Mechanical Engineering, Shandong University,Jinan 250061, China)

Abstract:In order to research the influence of coating on tool temperature during cutting, so as to provide theoretical basis for the design of tool coating,the generation of cutting heat and the tool boundary condition in the high speed cutting process are analyzed, and the physical and mathematical models of single-coated tool heat conduction are built. The interior temperature distribution formula of single-coated tool in the orthogonal high speed cutting process is derived by using mathematical analysis method.Analytical calculations of the cutting temperature distributions of TiN, TiC,Al2O3 coated tools are carried out by using the derived temperature formula,and the result of analytical calculation is compared with that of numerical analysis. The comparison shows that they are in good agreement. The thermophysical properties of coating material and substrate material and the thickness of coating have important influence on temperature rise. With the increase of heat flow density, the influence of coating thickness on the interior temperature of tool is enhanced.

Key words:High speed orthogonal cutting Single-coated cutting tools Transient temperature distribution

PP. 187-193

Design of Device and Experiment on Magnetic Field Assisted Electrochemical Machining

FAN Zhijian1WANG Ganggang2TANG Lin1WANG Tiancheng1

(1. School of Mechatronic Engineering, Xi’an Technological University, Xi’an 710032, China;2. Military Representative Office of PLA in 211 Factary,Beijing 100076, China)

Abstract:To improve flow field in the gap of electrochemical machining(ECM), a series of ECM devices are designed with magnetic circuit embedded inside the clamp lining and permanent magnet inlaid on the cathode sidewall for electrolytic shaping and machining shaped-hole respectively. Finite element analysis (FEA) is applied and experiments are carried out. The configuration with the multi-body gradually changing magnetic circuit is ascertained for electrolytic shaping. The experiments demonstrate that machining results are improved significantly with the shape error of the curved surface less than 0.05 mm, the surface roughness Ra0.2 μm. When magnetic circuit with N, S alternately arranged is inlaid on cathode the endlong veins on the sidewall of shaped-hole are decreased effectively and the specimen surface roughness is Ra0.8 μm. The magnetic field is applied in the direction that magnetic flux could perpendicularly cut flow streamline, so that Lorentz force is conducive to the spreading out of the flow beam, thus improving the surface roughness and the accuracy markedly.

Key words:Electrolytic shaping Electrolytic shaped-hole Magnetic field Flow field

PP. 194-198

Vol. 46, No. 2, 2010

Functional Tolerance Specification Design Based on Assembly Positioning

YANG Jiangxin1,2XU Xusong1,3CAO Yanlong1,2LIU Yancong3

(1. Institute of Manufacturing Engineering, Zhejiang University,Hangzhou 310027, China;2. Zhejiang Province Key Laboralory of Advanced Manufacturing Technology, Hangzhou 310027, China;3. College of Mechanical and Electronic Engineering,China University of Petroleum (Huadong), Dongying 257061, China)

Abstract:To study the functional tolerance specification methods consistent with the new generation of geometrical product specification(GPS), the class of positioning joints of part assembling and the principle of determining its priority are studied on the basis of definition of invariance class of GPS. The existing assembly oriented graph (AOG) is reformed and the expression of assembly positioning constraint is added in AOG. The methods of representing and decomposing of functional geometrical requirement are studied. And, the tolerance specification technology of interface between part-part based on the improved AOG is studied. A new functional tolerancing method from geometrical functional requirement to geometrical specification is presented. Tolerance specification example of an assembly is adopted to verify the feasibility of the proposed method.

Key words:Functional tolerance Tolerance specification design Assembly positioning constraint

PP. 1-8

Analysis of Ultrasonic Sound Field Characteristic with FDTD

ZHOU Zhenggan1,2WEI Dong1,2

(1. Institute for Nondestructive Testing and Mechatronics Engineering,Beihang University, Beijing 100191, China;2. Aeronautic Science Key Laboratory for Aeronautic Testing and Evaluation, Nanchang Hangkong University,Nanchang 330063, China)

Abstract:Ultrasonic non-destructive testing result is correlative with ultrasonic transducer sound field characteristic, and numerical method can effectively analyze ultrasonic sound field characteristics. Finite difference time-domain method(FDTD) is used to analyses 2D fluid kinetic equation,FDTD model is described. Perfect matched layer method is used to achieve boundary condition and obtain desired absorbing effect.Ultrasonic sound field propagation and disc sound source characteristic is researched through numerical calculation and simulation, effectiveness and feasibility of the algorithm is confirmed in comparison with other research results. Numerical simulation and practical measurement test is accomplished in focal ultrasonic transducer with pulse stimulated. There is good consistency existing in experiment result of sound field characteristic in axial cross section.

Key words:Finite difference time domain method Ultrasonic sound field Perfect matched layer

PP. 9-13

Fluctuation Analysis of Process Flow Based on Error Propagation Network

LIU Daoyu JIANG Pingyu

(State Key Laboratory for Manufacturing Systems Engineering,Xi’an Jiaotong University, Xi’an 710049, China)

Abstract:It is a key issue to reduce process fluctuation for improving machining quality of workpiece. For multistage machining processes, it is difficult to identify the fluctuation sources of process flow due to the complicated interactive effects among different stages. In view of this issue, a fluctuation evaluation and identification method is proposed based on machining error propagation network. A fluctuation propagation equation of process flow is established, and a machining error propagation network is constructed, which consists of machining form feature and machining element nodes. Based on this, fluctuation propagation coefficient is defined, and node state variation risk (NSVR) of different node is measured, and the priority of node can be identified according to its NSVR. A three stage process of a box part is used to verify the proposed method.

Key words:Process flow Machining form feature Machining error propagation network Fluctuation identification Node state variation risk(NSVR)

PP. 14-21

Experimental Research on Acoustoelastic Effect of Ultrasonic Guided Waves in Prestressing Steel Strand

LIU Zenghua LIU Su WU Bin ZHANG Yinong HE Cunfu

(College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology,Beijing 100124, China)

Abstract:Stress loss in steel strands will threaten the safety of whole prestressed structures. Therefore, it is important to achieve in-service prestress measurement nondestructively of steel strand in engineering.Prestress measurement method in steel strand based on ultrasonic guided wave technique is analyzed theoretically and verified in the experiment.According to wave theory and acoustoelastic theory, longitudinal and shear wave velocities in steel strand under different applied prestress levels are obtained, the relationship between group velocity of the lowest longitudinal guided mode L(0,1) and applied stress in steel strand is analyzed and constructed. In experiment, L(0,1) mode of ultrasonic guided waves is excited and received by a pair of self-developed magnetostrictive sensors in a seven-wire, 17.80 mm nominal diameter steel strand under different applied prestress levels. Group velocities of L(0,1) mode under different stress state conditions are measured in the steel strand and the actual relation curve between experimental group velocities of the mode and applied stresses in the steel strand is obtained. Results show that group velocity of L(0,1) mode will decrease approximately linearly with the increase of applied stress when the stress is above 0.5 GPa. Experimental results are well coincident with predicted assumption. The conclusion provides a certain experimental foundation for application of ultrasonic guided waves technique to measurement of applied prestress in steel strand.

Key words:Steel strand Ultrasonic guided waves Longitudinal mode Acoustoelastic effect Prestress

PP. 22-27

Study on Wavelet Threshold Denoising Algorithm Based on Estimation of Noise Variance

QU Weiwei GAO Feng

(School of Transportation Science and Engineering,Beihang University, Beijing 100191, China)

Abstract:Noise of signal not only reduces the quality of signal but also interferes the validity of correlative arithmetic seriously. Therefore,effective and robust estimation of noise variance is very important for various signal processing. A new method is proposed to estimate noise variance. A Gaussian mixture model (GMM) is used to model the high frequency wavelet coefficients (HFWC). The parameters of the mixture model are obtained with the EM iterative algorithm. The HFWC will be classified as noises class and edges class in the GMM when the parameters meet a certain condition. Based on the correlation among HFWC, GMM is used again to classify the coefficients of the noise as well as to take the noise estimation. Finally, the variance of noise signals is calculated and regarded as the noise variance estimation of original signal. Based on the estimation algorithm, wavelet threshold denoising is applied to reverse engineering. The denoising effect of practical signal is perfect in smoothness and feature preserving. The examination indicates that this estimation method of noise variance has certain adaptability to different noise, moreover, the denoising method of wavelet threshold can be simply achieved and applied in most situations.

Key words:Estimation of noise variance Gaussian mixture model Correlation of the coefficients Wavelet threshold denoising

PP. 28-33

Summary of Virtual Rolling Technology Research

WANG Yiqun CHEN Chunming ZHANG Wei YANG Yang

(College of Mechanical Engineering, Yanshan University,Qinhuangdao 066004, China)

Abstract:Based on the development of computer simulation technology,the development of virtual rolling technology at home and abroad since 1990s is summarized. The integral frame system of virtual rolling is analyzed, and the limitations of present virtual rolling simulation research are pointed out. Virtual rolling technology, which is a large-scale software and hardware integration simulation system, can research the static and dynamic characteristics of the rolling mill by using numerical analysis method. It describes roll mill system in the form of a mathematic model, and makes up a large-scale system according to information regulation, and confirms some uncertain flexible parameters and non-linear cells by means of system identification method. Based on the advanced modeling,multi-field simulation, information management, interactive user interface and virtual reality techniques, the virtual rolling system can complete equipment simulation, control simulation and management simulation. It not only can provide technical support to designing new rolling mills and transforming existing rolling mills, but also can explore optimum process parameters and control model of existing equipment in order to improve the quality and output of products. Its development direction is pointed out.

Key words:Computer simulation Virtual rolling technology Present development state Future prospects

PP. 34-39

Mechanism of Fatigue Damage Evolution and the Evolution Law

XU Jinquan GUO Fengming

(Department of Engineering Mechanics, Shanghai Jiao Tong University, Shanghai 200240, China)

Abstract:It is well known that fatigue is induced by the internal damage evolution of material. However the mechanism of damage evolution remains unclear yet. From the thermal disturbance of atomic motion, when the active energy of an atom is greater than a certain critical value, the atom will escape from its original equilibrium position and thereby a void will be generated.Under cyclic loadings, the voids generated by the thermal disturbance cannot be completely annihilated, so that the damage will be initiated or accumulated. From this view, the mechanism of damage evolution can be well explained, and the damage accumulation rate can be theoretically related to the rate of the statistical process of atomic escape. Therefore, this view provides the way to set up the damage evolution law with theoretical foundation. The evolution law based on this mechanism can well indicate the already known damage-life relationships of metals. Taking the experimental relationships between the damage and fatigue life under symmetrical cyclic loadings with different stress amplitudes into account, the damage evolution law is deduced in details. Furthermore, the accumulating rule of damage is also discussed on the basis of the proposed damage evolution law.

Key words:Fatigue Mechanics of damage Damage evolution Mechanism Fatigue life

PP. 40-46

Simulation of Polymer Extrusion Swelling by Using Iterative Stabilized Fractional Step Algorithm

WANG Wei1,2LI Xikui1HAN Xianhong3

(1. State Key Laboratory of Structural Analysis of Industry Equipment,Dalian University of Technology, Dalian 116023, China;2. Key Laboratory of Rubber-plastics, Ministry of Education,Qingdao University of Science & Technology,Qingdao 266042, China;3. Department of Plasticity Forming Engineering, Shanghai Jiao Tong University, Shanghai 200030, China)

Abstract:With the introduction of the finite incremental calculus procedure a pressure stabilized mass conservation equation is reconstructed to overcome spurious oscillations of resulting pressure spatial distribution due to incompressibility of fluids. The discrete elastic viscous stress splitting method is used to retain an elliptic contribution in the weak form of the momentum equation in the absence of a purely viscous contribution or as the viscous contribution is negligible in comparison with the viscoelastic contribution. Inconsistent streamline upwinding method is employed to spatially discretize the constitutive equation of the Phan-Thien-Tanner viscoelastic constitutive model. The mass, momentum and constitutive equations are discretized and solved by the iterative stabilized fractional step algorithm based on Crank-Nicolson implicit difference scheme. The moving free surface is captured and determined in terms of the stream function. The isothermal extrusion swelling simulations for low density polyethylene and linear low density polyethylene melts are investigated. Numerical results demonstrate good agreement of numerical results obtained by the proposed algorithm with those given in the literature and experiment results.

Key words:Viscoelastic flow Finite element method Fractional step algorithm Extrusion swelling

PP. 47-54

Experiment and Numerical Simulation of Size Effects of Mechanical Behaviors of Lead-free Micro-interconnection Solder Joints

YIN Limeng ZHANG Xinping

(School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China)

Abstract:The size effect of mechanical behaviors and performance evolution of micro-scale interconnects prepared by lead-free Sn-Ag-Cu solder with different joint sizes are investigated by a sophisticated micro-tension experiment and finite element simulation. The results show that the tensile strength and fracture strain of the joints increase with decreasing joint diameter (475～200 μm) while keeping joint thickness constant (225 μm), and strength values of the joints are obviously higher than that of the bulk solder. For the joints with large diameter, the fracture occurs in interfaces of the joints and shows low ductility, in contrast to necking type fracture with large deformation happened in the mid of the joints having small diameter. Numerical simulation results show that due to the different levels of mechanical constraint in the solder joints, the small diameter joint has relatively low interface stresses and the maximum stress locates in the mid of the joint where the final fracture usually occurs, thus the joint would exhibit high fracture strength; while for the large diameter joint,the maximum stress locates in the interfaces where cracks easily initiate and grow in intermetallic compound layer through the interfaces at a low level of applied stress, and consequently the strength of the joint will be low.

Key words:Lead-free solder Micro-interconnect joints Mechanical properties Size effects Finite element simulation

PP. 55-60

Kinematic Error Modeling for Tailored Blank Laser Welding Machine Based on the Improved MBS

XIN Liming1,2XU Zhigang1ZHAO Mingyang1ZHU Tianxu1

(1. Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China;2. Graduate School, Chinese Academy of Sciences,Beijing 100039, China)

Abstract:Research on error modeling of tailored blank laser welding machine which has four linear axes is introduced. The number arrays of low-order body are used to describe the topological structures which are taken to generalize and refine MBS, and the characteristic matrices are employed to represent the relative positions and gestures between any two bodies in MBS. Position error transfer function which can reflect the influence of each error origin on the positioning error of the machine tool is given to describe transmission error of the machine in detail. Based on this method, the error model of the tailored blank laser welding machine is put forward. The measurement and evaluation of their error parameters start, after completed error modeling of the machine. Leica laser tracker is introduced to measure the errors of the machine and to check the result of the error model. The comparison results indicate that the error model can effectively predict errors of the tailored blank laser welding system.

Key words:Tailored blank laser welding Multi-body system theory Error modeling Position error transfer function Laser tracker

PP. 61-68

Research on Digital Human Model System Used for Heavy Commercial Vehicle Ergonomic Design

REN Jindong1WANG Dengfeng1WANG Shanpo2LIU Guoqiang2CAI Lili1

(1. College of Automotive Engineering, Jilin University,Changchun 130022, China;2. China National Heavy Duty Truck Group Corporation,Jinan 250001, China)

Abstract:A generic framework of digital human model system is studied by adopting the knowledge of anthropometry, multi-body system kinematics, computer graphics and ergonomics. The problems during the application of current digital human models in vehicle ergonomic design are analyzed, which are taken into account in subsequent research.Theories and corresponding techniques about how to use human data during design process to ensure enough accommodation level are studied.The content, method and performance evaluation of heavy commercial vehicle ergonomic design are studied and summarized. Based on the above mentioned theories and techniques, the system for heavy commercial vehicle ergonomic design (SHOVED), a digital human model system used for ergonomic design of heavy commercial vehicle, is developed, including functions of human modeling, vehicle modeling, scheme design, scheme analysis and optimization. By application of SHOVED, not only heavy commercial vehicle ergonomic design process can be done effectively and perfectly, but also the level of target people accommodation can be held accurately. The profile, constitution, key techniques and application principle of the generic digital human model framework and SHOVED are presented.Prospects for further study are given.

Key words:Digital human model Heavy commercial vehicle Ergonomics

PP. 69-75

Model and Architecture of Hierarchical Reinforcement Learning Based on Agent

WANG Wenxi1XIAO Shide1MENG Xiangyin1CHEN Yingsong1ZHANG Weihua2

(1. School of Mechanical Engineering, Southwest Jiaotong University , Chengdu 610031, China;2. Traction Power State Key Laboratory, Southwest Jiaotong University, Chengdu 610031, China)

Abstract:By introducing frequency maximum Q heuristic learning algorithm, a hierarchical reinforcement learning method is improved, this method solves the problem of agent optimal strategy learning in a large scale state space and dynamic changing environment. Bringing attribute maintenance operator, the attribute of promise and layout into the classical belief, desire, intention(BDI) model, which is modified to increase the adaptability and in-line learning ability of agent, the rational maintenance process of consciousness attribute is given. A new agent system and architecture with initiative, autonomy, adaptability and sociality is proposed,and a new path planning agent (APP) is developed on the basis of this architecture. Through setting the configuration of drive environment, the complicated vehicle drive state is simulated, and through continuous learning of the drive state, the optimal path is obtained finally, and then the feasibility and effectiveness of the new architecture are verified.

Key words:Agent Reinforcement learning Architecture Consciousness model

PP. 76-82

Simulation Analysis of Car A-alloy Wheel 13°Impact Test

ZANG Mengyan1,2QIN Tao1,2

(1. School of Mechanical ＆ Automotive Engineering,South China University of Technology, Guangzhou 510640, China;2. Guangdong Provincial Key Laboratory of Automotive Engineering, Guangzhou 510640, China)

Abstract:It is very necessary to replace experimental test by a numerical model of wheel impact test in order to reduce experimental times and improve design efficiency. A finite element model of A-alloy wheel impact test is established based on fully consideration of static and dynamic behaviors of impact test stand. The whole model includes impact block, wheel & tire assembly and test stand. The rubber supports are simulated by using spring-damper elements, and the prestressing of the wheel & tire assembly is applied as the initial condition, the impact process is solved by the transient dynamic explicit finite element software LS-DYNA. The simulation model is verified by comparing the simulation results with experimental results of the strain on some measuring points. It is obvious that finite element models have a guiding significance and practical value for initial design and development of the A-alloy wheel.

Key words:Finite element method Car A-alloy wheel Computer simulation Impact test

PP. 83-87

Thermo-mechanical Coupling Simulation of Braking Process of Brake Disc

YANG Zhiyong HAN Jianmin LI Weijing CHEN Yue WANG Jinhua

(School of Mechanical, Electronic and Control Engineering,Beijing Jiaotong University, Beijing 100044, China)

Abstract:On the basis of the part-disc indirect coupling method, the full-disc indirect coupling model, the symmetry features of the structure of brake disc and symmetry constraints applied during the stress calculation are taken into account, the elastic-plastic thermo-mechanical coupling contact models including brake disc, pad and hub is established, so that the relative movement between the brake disc and pad is realized. The model can become the interaction and direct coupling simulation between temperature fields and stress fields. By the comparison of the simulation results and the experimental results, it can be concluded that the simulated distributions of the temperature and stress fields of brake disc is consistent with the actual distributions during braking. The formation of hot spots on the brake disc during broking is investigated by using the elastic-plastic thermo-mechanical coupling method.

Key words:Brake disc Elastic-plastic thermal-mechanical coupling Hot spot

PP. 88-92

Model of Lean Production System for Automobile Manufacture Enterprise

ZHANG Genbao1,2FU Xinglin2ZHU Yuqing2REN Xianlin2

(1. Key Laboratory of Automobile Part Manufacturing,Checking and Measuring Technology of Ministry of Education,Chongqing University of Technology, Chongqing 400050, China;2. College of Mechanical Engineering, Chongqing University,Chongqing 400030, China)

Abstract:Many enterprises still don’t know how to combine it with Chinese enterprise’s practice for this exotic. Based on extensive investigation of automobile manufacture enterprises for these problems that exist in the process of implementing lean production and the basic principle of lean production, a lean production system model that consists of behavior criterion, leadership, worker training, work group, total production maintenance, manufacturing engineering, in-station process control, industrial logistics, synchronization logistics, safety, environment and quality operation system is designed for Chinese automobile enterprises. Meanwhile the system file structure, implementation model and evaluation model of lean production system are designed to guarantee this lean production system model effectively implementing, tracking and evaluating the effect. Finally, it is proved that this model is feasible through practical application in automobile enterprises.

Key words:Lean production Automobile manufacture enterprise Evaluation system Toyota production system Model

PP. 93-98

Optimization Design of Water-cooled Heat Sink Applied to Large-capacity Power Electronic Equipment

JIE Guisheng SUN Chi WANG Guangsen NIE Ziling MENG Qingyun

(Institute of Power Electronics Technology, Naval University of Engineering, Wuhan 430033, China)

Abstract:In order to enhance the heat-transfer capability and control the temperature uniformity of the water-cooled heat sink, the relations between the dimensionless thermal resistance and three channel parameters(the number of channels, fin height and fin duty ratio of the heat sink are deduced theoretically in laminar flow range on the condition that the outline dimensions of the heat sink with plate fins and the fluid volume flow are chosen firstly. Then, a parameter optimizing design method with application to arbitrary heat sink dimensions which is of good directive significance in engineering is presented according to these variation relations. The results of simulation and experiment prove the effectiveness of the method and show that, the heat-sink with small channel sizes can reach higher heat-transfer efficiency and is more effective to cool the component with big heat-flux density, the heat-transfer efficiency decreases with the increase of volume flow, so the volume flow should be selected reasonably with comprehensive consideration of the control requirements of the heat-sink flow resistance and fluid mean temperature rise.

Key words:Power electronics Water-cooled heat sink Computational fluid dynamics(CFD)Optimization design

PP. 99-105

Computational Analyses on Aerodynamic Characteristics of Flatback Wind Turbine Airfoils

YANG Rui1,2LI Rennian1,2ZHANG Shiang1,2LI Deshun1,2

(1. Fluid School, Lanzhou University of Technology,Lanzhou 730050, China;2. Engineering Center for Wind Turbines of Gansu Province,Lanzhou 730050, China)

Abstract:The flatback wind turbine airfoils have good structure and aerodynamic performance. Blunt trailing edge or flatback airfoils are studied especially for the inboard region of large wind turbine blades. The drawback of the flatback design is known as the production of large vortices downstream of the airfoil that tend to degrade the performance of the blade. The overall objective of the present research is to have a better understanding of the airfoil performance characteristics such as the loss in aerodynamic performance balanced by the structural performance gain.The performance of the S809-100 flatback airfoil is simulated and compared with the original thin-trailing edge S809 airfoil by using the computational fluid dynamics (CFD) technique. It is shown that the flatback airfoil can increase the sectional maximum lift coefficient and lift curve slope, and reduce the well-documented sensitivity of the lift characteristics of thin airfoils to surface soiling in comparison with the traditional thin trailing edge airfoil.

Key words:Flatback airfoils Wind turbine Aerodynamic performance Computational fluid dynamics

PP. 106-110

Research on Cryogenic Character of Spatial Low Infrared Radiated Cold-shield with Liquid Nitrogen

ZHANG Zhouwei1LI Yanzhong1WANG Yahong2CHEN Guangqi3GE Ruihong3PAN Yanpin3

(1. School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China;2. Technique Department, Lanzhou Power Station & Vehicle Institute,Lanzhou 730050, China;3. Lanzhou Institute of Physics, National Key Laboratory of Vacuum& Cryogenics Technology and Physics, Lanzhou 730000, China)

Abstract:Using the cryogenic cold shield method can decrease the exterior infrared intensity of spacecraft. A model of layered reservoir and gas-liquid separated spatial cold-shield is established. Numerical simulation parameters of flow field are used to calculate the empirical heat convectional relations and obtain convectional coefficients on different boundary conditions, and by substituting different boundary conditions to steady-state heat-transfer simulation process, the regularity of temperature distribution in gas area and liquid area is obtained. A unit heat transfer test model is established, and equivalent radiation method is used to analyze the consistency of the test model in ground and in space. The results show that the maximum temperature reaches 92.9 K from heat-transfer simulation, 107 K from flow-field simulation, and 180 K from experiment in extreme condition when the height of layered reservoir is less than 100 mm. The experimental temperature gradients are similar to the simulated results in shape but larger than simulated results due to the influence of equivalent radiation. The equivalent radiation is close to 1 592.6 W/m2,liquid nitrogen maintains 15min on the ground and more than 30 min in space. The layered reservoir model can make the surface temperature of aircraft lower than 100 K and the infrared radiation lower than 0.5 W/m2in specific time period in space.

Key words:Cold shield Infrared radiation Equivalent radiation Liquid nitrogen

PP. 111-118

Research on Behavior and Modeling of Absorption Chiller

ZHANG Xiaohui1WU Jinquan2

(1. School of Physical Science and Technology, Soochow University,Suzhou 215006, China;2．Department of Mechanical Engineering, National University of Singapore, Singapore 117576, Singapore)

Abstract:An off-design quasi-theoretical model of absorption chiller performance is derived by combining theoretic and experimental methods.Due to the description of measurable parameters (evaporator outlet temperature, generator inlet temperature and condenser inlet temperature)in the mathematic model, the requirement of a large number of detailed parameters could be avoided, which makes this method more practical for system analysis and comparison. An advantage of the model lies in its generality. Based on experimental data, the coefficients can be determined,so it is suitable for use. It can also be used to study and analyze the off-design general characteristics of absorption chiller. The prediction values of coefficient of performance(COP) under partial load are compared with detailed experimental data from a set of commercial chillers. The maxzimum relative standard deviation is less than 10%, The agreement between theory and actual performance data confirms that the model is valid. Typical partial load performances are summarized and it is found that for absorption chiller, when COP and cooling capacity are expressed as the ratio to their design values, the set of performance curves of 1/COP against 1/(cooling rate) for a series of absorption chillers can be integrated into a single curve in partial load, also the model can be expressed in a non-dimensionless form, which indicates that similarity exists for a set of absorption chillers.

Key words:Thermodynamics Modeling Absorption chiller Similarity

PP. 119-125

Hybrid Neural Network Prediction Model of Hydraulic Valve Characteristics Under the Affection of Multiple Geometric Factors Effected

JIA Zhenyuan MA Jianwei LIU Wei WANG Fuji

(Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education, Dalian University of Technology, Dalian 116024, China)

Abstract:Hydraulic valve system is a complex system with multiple characteristics affected by multiple geometric elements. It will be essentially important to the manufacture process to establish the prediction model of the system characteristics by using the geometric elements and achieve the goal of prediction. On the basis of synthesizing the features of the back propagation (BP) neural network and RBF neural network, a prediction model which is a new hybrid neural network based on the BP neural network and radial basis function (RBF) neural network is presented. And the hybrid neural network is trained by using data measured from actual production. The calculation results show that the hybrid neural network prediction model can improve the prediction accuracy of a single neural network model, and reach an average relative error of 0.046 1. Therefore the proposed hybrid neural network can well satisfy the requirement of predicting the hydraulic valve characteristics.

Key words:Multiple geometric elements Hydraulic valve system Hybrid neural network Combined prediction model

PP. 126-131

Energy-saving Technology of Variable Counterweight and Its Energy Consumption Analyses

YANG Huayong1HU Dongming1,2XU Bing1

(1. The State Key Lab of Fluid Power Transmission and Control,Zhejiang University, Hangzhou 310027, China;2. Zhejiang Provincial Special Equipment Inspection and Research Institute, Hangzhou 310020, China)

Abstract:To solve the disadvantages of high energy consumption and low efficiency in hydraulic lift system, an innovative energy-saving technology of variable counterweight is proposed. The energy-saving concept is given and the working principles of two kinds of variable counterweight system are introduced, namely variable hydraulic counterweight and mechanical counterweight with variable speed. And the system applying the variable hydraulic counterweight is discussed in detail,including the installed power, the energy consumption, the efficiency and the poor working condition. Compared with the conventional variable voltage variable frequency (VVVF) hydraulic system, the installed power and energy consumption of the system with variable hydraulic counterweight decreases by 67% and 35% respectively, and the efficiency increases 30%, which means the system saves energy remarkably. Then the problems of the system are discussed, mainly involving efficiency,dynamic response and so on, and the solutions are presented. Finally, the development of the variable counterweight technology is prospected.

Key words:Hydraulic lift system Energy consumption Energy-saving Varying counterweight Variable voltage variable frequency (VVVF)

PP. 132-138

Numerical Investigation on a New Type of Fully Reversible Axial Fan with Two Blade Rows on Both Sides of the Rotor

LI Jingyin1CHEN Weiwei1LÜ Feng2

(1. School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China;2. Daya Bay Site, China Guangdong Nuclear Power Company, Ltd.,Shenzhen 518031, China)

Abstract:The fully reversible axial flow fans, which can rotate reversibly to ventilate in the opposite direction with the same performance curves,are widely demanded in subways, tunnels, underground warehouses and many other fields. A new configuration method, which can obviously improve the efficiency of reversible axial flow fans, is proposed to meet this special requirement. The new approach is to install two rows of blade with reverse symmetrical airfoil section at stagger angle of 90° on both sides of the rotor of reversible axial fans. The same computational domain is used for reversible flow fans with and without the two-row guide vanes,and the detailed numerical studies reveal that the upstream blade row has little influence on the direction of the incoming flow while the downstream blade row working as a straightener reduces the circumferential velocity of the rotor-exit air remarkably and makes the outlet air flow in nearly axial direction in the diffuser. This leads to a greatly decreased friction loss, and the greater the rate of divergence in the diffuser is, the more obvious the effect will be. In addition, part of the swirl dynamic energy of the rotor-exit air is recovered and changed into static pressure rise. The above two mechanisms contribute to the evident increase in both total pressure rise and efficiency of the new type of reversible axial fans with additional blade rows than those without any stators. Furthermore, the installation of the blade rows on both sides of the fully reversible axial fan guarantees a symmetric configuration and consequently guarantees the fully reversible performance also.

Key words:Reversible axial-flow fan Reverse symmetrical airfoil Numerical simulation

PP. 139-144

Simulating and Extending Wire Electrical Discharge Machining Reliability Data by Radial Basis Function Neural Network

JIA Zhixin1ZHANG Hongbin1,2XI Anmin1

(1. School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, China;2. Department of Airborne Equipment, Army Aviation Institute,Beijing 101114, China)

Abstract:For determining the distribution model of wire electrical discharge machining (WEDM) reliability data, the radial basis function(RBF) neural network is applied to simulating the original reliability data,and more reliability data are achieved that have the same distribution rules with the original reliability data. The cluster learning algorithm is chosen as the learning method of the neural networks. The data centers of hidden nodes are determined by unsupervised learning, and the extended constants of the hidden nodes are determined by the distances of each data center, then the output weights of the hidden nodes are achieved by the supervised learning method. After simulating and calculating, the extended reliability data is achieved by the trained RBF neural networks,and the reliability distribution model of WEDM reliability data is confirmed as log-normal distribution model by the graphical estimation method and Kolmogorov-smirnov (K-S) test method. And it is more accurate for estimating characteristic parameters of the reliability distribution model.

Key words:Radial basis function neural network Reliability Wire electrical discharge machining Cluster learning algorithm Kolmogorov-smirnov test method

PP. 145-149

Remaining Life Evaluation Based on Accelerated Life Testing

TAN Yuanyuan ZHANG Chunhua CHEN Xun WANG Yashun

(College of Mechatronics Engineering and Automation,National University of Defense Technology,Changsha 410073, China)

Abstract:Remaining life evaluation of products based on accelerated life testing (ALT) is becoming a hot spot of research, and how to improve the precision of evaluation is one of the most important issues. Related tasks on remaining life evaluation based on ALT, however, exist some problems,such as regarding the samples as new products, taking the extrapolated condition from ALT as the real operated condition, and neglecting field data. In view of these problems, a more accurate life model is built by taking the impact of initial failure and environment difference into account.The model is statistically analyzed by fusing ALT testing data and field data, so as to increase much more multisource life information within evaluated data. Simulation shows that, the result of remaining life evaluation based on ALT becomes more precise due to improving life model and increasing information.

Key words:Remaining life evaluation Accelerated life testing Monte Carlo simulation Initial failure Data fusion

PP. 150-154

Robust Design of Structural Fatigue Life

LI Feng MENG Guangwei ZHOU Zhenping ZHOU Liming

(College of Mechanical Science and Engineering, Jilin University,Changchun 130022, China)

Abstract:Due to the random factors such as material properties,geometrical characteristic of structural member, load history and environmental condition, the fatigue life of structure often deviates from the design life. To reduce the scatter of fatigue life, a robust optimization model of structural fatigue life is presented. The model combines structural optimization theory and stochastic finite element method. Under the condition of considering the effects of variance of design variables and other random variables on the structural fatigue life, the problem is formulated as a multi-criteria optimization problem, in which both the mean structural fatigue life and the standard deviation of structural fatigue life are to be minimized. The relationship between the mean structural fatigue life and the standard deviation of structural fatigue life can be balanced by a weight factor. The structural fatigue life is limited between the low fatigue life and high fatigue life in the constrain functions. Fatigue life of the structure optimized by the proposed method has a relative small fluctuation at the mean value and keeps far away from the ultimate fatigue life. A numerical example is performed for a planar 10-bar truss. The result shows that the proposed method is feasible and applicable.

Key words:Robust design Fatigue life Structural optimization Stochastic finite element method Randomness

PP. 155-158

Moving-gimbal Effects Compensation of Double Gimbal Magnetically Suspended Control Moment Gyroscope Based on Compound Control

WEI Tong1,2FANG Jiancheng1,2LIU Zhurong1,2

(1. School of Instrumentation Science & Opto-electronics Engineering,Beihang University, Beijing 100191, China;2. Key Laboratory of Fundamental Science for National Defense of Novel Inertial Instrument and Navigation System Technology,Beihang University, Beijing 100191, China)

Abstract:Double gimbal magnetically suspended control moment gyroscope (DGMSCMG) is made up of magnetically suspended high-speed rotor system, inner and outer gimbal rate-servo system, and serves as novel attitude control actuator of spacecraft. Owing to nonlinearity and strong couple of three subsystems, rotor axis run-out will grow significantly to reduce system stability severely and response speed goes lower when gimbal revolving, which is called moving-gimbal effects.The effects influence DGMSCMG function severely and must be depressed. Based on DGMSCMG dynamic model set up in this paper and couple mechanism analysis, a novel compensation method based on compound control is presented, which introduces feedback of gyro item and feedforward of preset gimbal rate to depress additional displacement of rotor and raise response speed of gimbal, and system global stability is analyzed. Results of simulation and experiment show that the proposed method can depress moving-gimbal effects effectively to satisfy DGMSCMG requirement besides remaining stability.

Key words:Double gimbal magnetically suspended control moment gyroscope Magnetic bearing Gyroscope effect Dynamic coupling Moving-gimbal effects Compound control Linearization

PP. 159-165

Trajectory Planning and Precision Control of Scan-move for Step-scan Lithography Stage

MU Haihua1,2ZHOU Yunfei1ZHOU Yanhong2

(1. State Key Laboratory of Digital Manufacturing Equipment& Technology, Huazhong University of Science & Technology,Wuhan 430074, China;2. College of Computer Science & Technology, Huazhong University of Science & Technology, Wuhan 430074, China)

Abstract:A trajectory planning method and precision control strategies for scan-move of step-scan projection lithography are investigated. The difference of trajectory planning between step-move and scan-move is firstly discussed. Aiming at the requirements of accuracy and strict synchronization of scan-move, several key issues are analyzed.Considering the accuracy losses in discrete-time implementation of trajectory planning algorithm, the integration strategy in discrete-time domain of precision control of trajectory planning is presented with combination of internal integer integration strategy. Furthermore, a compensation method with a correcting factor of constant velocity scan phase is advanced. Experiment results demonstrate that the proposed trajectory planning algorithm and its precision compensation strategy are accurate and effective. These methods are successfully applied in ultra-precision motion control system of 100 nm step-scan projection lithography equipment.

Key words:Scan-move Trajectory planning Precision control Discrete-time integration

PP. 166-171

Suppression of Disturbance from Test Turntable Dynamic Unbalance by Using Adaptive Repetitive Control

XU Fengxia1,2ZHAO Xuezeng2LU Zhongda1

(1. Institute of Computer and Control Engineering, Qiqihar University,Qiqihar 161006, China;2. School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China)

Abstract:Through analysis of dynamic unbalance factors of a three-axis test turntable, it is found that the test turntable has periodic disturbance torque. The periodic disturbance torque mainly consists of acceleration torque, coriolis coupling torque and centrifuge coupling torque, which is related to three-axis moment of inertia, position angle and rotating speed of test turntable and will influence the positioning precision and speed precision of test turntable. In order to suppress the periodic disturbance torque with uncertain frequency caused by dynamic unbalance of three-axis test turntable, an adaptive finite-dimensional repetitive control used to eliminate periodic disturbance is proposed. Adaptive algorithm is adopted for on-line identification of disturbance frequency, and finite-dimensional repetitive controller parameters are adjusted to eliminate the disturbance. The convergence of the algorithm and the stability of the system are proved by using averaging method.Simultaneously the algorithm can eliminate multi-period disturbance of different frequency by regulating the structure of adaptive multi-period finite-dimensional repetitive controller. Simulation results show that the proposed method can effectively suppress period disturbance caused by dynamic unbalance of three-axis test turntable and improve the positioning precision and speed precision of test turntable system.

Key words:Three-axis test turntable Dynamic unbalance Period disturbance Adaptive algorithm Finite-dimensional repetitive control

PP. 172-177

Mental Construction of User Perception Image in Product Design

ZHANG Yanhe1,2YANG Ying2LUO Shijian2PAN Yunhe2

(1. College of Arts, South China Agricultural University,Guangzhou 510642, China;2. College of Computer Science and Technology,Zhejiang University, Hangzhou 310027, China)

Abstract:In order to obtain the relationships among the product whole perception image (PWPI), the product sub-perception image (PSPI) and the product elements (PE), the formation mechanism of the user perception image (UPI) is analyzed in product design, and the UPI model of mental construction is proposed. By taking the sun glasses as an example, the mapping relationship between the PWPI and four PSPI i.e.form, color, material and shade, is built by applying the multivariate adaptive regression splines. And then the optimum combination of the four PSPI is solved in Matlab software by using the most approximate and the lowest image-value rules. The relation model between PE and each PSPI is established by making use of the regression tree. The optimal PE combination related to the optimum four PSPI is further obtained on the basis of UPI interval. And then the optimum PE combination related to certain UPI is obtained. The study shows that, in the mental construction of the user perception image, there is complicated relationship between PWPI and PSPI, and the tree structure can represent the relation between PSPI and PE.

Key words:User perception image Industrial design Product elements Regression tree Multivariate adaptive regression splines

PP. 178-184

Real-time Model Checking of Dynamic Temporal Consistency for Multi-process of Workflow

DU Yanhua1FAN Yushun2

(1. School of Mechanical Engineering , University of Science and Technology Beijing, Beijing 100083, China;2. Department of Automation, Tsinghua University,Beijing 100084, China)

Abstract:In the practical operation environment of an enterprise, there generally exist multiple parallel working processes, thus having resource conflicts among them. It is very important to model and verify dynamically the consistency of temporal constraints of multi-process with resource conflicts. Based on real time model checking technique，a dynamic checking method of temporal constraints for multi-process of workflows is proposed. Multi-process of workflows is modeled by using a time automata, and the temporal constraints to be checked are transformed as the queries of observer time automata models. When temporal constraints are checked, the models are updated according to the known temporal information, and temporal constraints are checked. The method is practicable, because it not only can deal with the modeling and analyzing of multi-process with resource constraints, but also is flexible,namely when the temporal constraints are modified, the corresponding observer time automata is changed. Furthermore, there are some tools and software of real-time model checking to support it.

Key words:Multi-process Temporal constraint Real-time model checking Time automata Dynamic checking

PP. 185-191

Static Postures Assessment Rule of the Steering Layout Design

HAN Ying1HONG Jun1WANG Wei2HAN Xiuli1WANG Xin1

(1. State Key Laboratory for Manufacturing Systems Engineering,Xi’an Jiaotong University, Xi’an 710049, China;2. Launch Engineering Department, Air Force Engineering University, Sanyuan 713800, China)

Abstract:This study presents an assessment system of human body discomfort index based on muscle hardness experiments— Assessment system based on muscle hardness experiments (ASMH), which is a guideline of the steering layout design. First of all, a group of experiments are carried out to find out the impact of human body static postures on muscle hardness index (MHI). In the process, relative muscle hardness value (MHV) are measured by muscle hardness gauge so that the variation rule of MHV in different operating postures is obtained. Based on the physiological feature that muscle hardness may result in muscle discomfort in human body, muscle discomfort index (MDI) is defined through the normalization, and weighting of MHV. Then concerning the motions of two and three degree-freedom joints, different calculation methods for the overall MDI are adopted. Accordingly, ASMH is proposed, which can provide more objective ergonomic suggestions. At last, through the comparison between ASMH and rapid upper limb assessment (RULA) which is widely adopted in engineering, it is proved that the accuracy and applicability of ASMH are improved. The range of score increases to 12 and the rank increases to 6. Therefore, ASMH is more effective in ergonomic design.

Key words:Steering layout design Static operating postures Muscle hardness Discomfort assessment system

PP. 192-198

Vol. 46, No. 3, 2010

Dynamic Dimensional Synthesis of Delta Robot

ZHANG Limin MEI Jiangping ZHAO Xueman HUANG Tian

(School of Mechanical Engineering, Tianjin University,Tianjin 300072, China)

Abstract:The dynamic dimensional synthesis of Delta robot widely used for high-speed pick-and-place operations is studied. On the basis of the inverse kinematic and rigid body dynamic formulation, a novel global dynamic performance index is proposed for minimizing the maximum driving torque of a single active joint. The proposed index can explicitly be expressed in terms of dimensional and inertial parameters as well as system configurations, allowing the singular configurations to be easily found. Various geometrical and performance constraints are taken into account in terms of workspace/machine volume ratio, lower and upper bounds of mapping characteristics in terms of velocity, accuracy and actuation rigidity between the joint space and the operation space. The effects of the performance constraints on the feasible domain of design variables and the performance index are investigated in depth via an example, enabling a set of optimized dimensional parameters to be obtained for achieving a good dynamic performance throughout the entire workspace.

Key words:Parallel robot Dynamic performance Dimensional synthesis

PP. 1-7

Static Stiffness Analysis of Flexible-cable-driven Parallel Mechanism

LI Hui ZHU Wenbai

(National Astronomical Observatories, Chinese Academy of Sciences,Beijing 100012, China)

Abstract:The static stiffness of flexible-cable-driven parallel mechanism is studied and its theoretical formulation of the calculation model is deduced. The results show that the static stiffness matrix of flexible-cable-driven parallel mechanism can be decomposed into two parts. k1results from the changes of position and orientation of the movable platform which correlates with cable tensions, while k2is caused by the deformation and deflection of cables. The study further proves that the static stiffness of completely restrained positioning mechanism(CRPM) or redundantly restrained positioning mechanism (RRPM)mainly depends on k2. It is only affected by the elastic performances of all cables and the Jacobian matrix which represents the vectors of cable forces, and unrelated with the amplitudes of cable tensions. For the incompletely restrained positioning mechanism (IRPM), because of the existence of cable catenaries the static stiffness not only correlates with the elastic performances of all cables and the Jacobian matrix, but also the amplitudes of cable tensions. Two examples concerning the static stiffness estimation are given for RRPM and IRPM(the cable-driven cabin suspension of the five-hundred-meter aperture spherical telescope)respectively. The comparison between the analytical and simulation results proves the validity of the calculation model.

Key words:Flexible-cable-driven parallel mechanism Static stiffness Five-hundred-meter aperture spherical telescope

PP. 8-16

Tracking Control of Cable-driven Parallel Robots Considering Cable Sag Effects

DU Jingli BAO Hong DUAN Baoyan

(School of Electromechanical Engineering, Xidian University,Xi’an 710071, China)

Abstract:Parabolic equation is utilized to represent the curve of a long span cable. The relationship among cable force, cable end displacement and cable length variation is derived by using parabolic equation.Dynamics model of cable-driven robots is established on the basis of cable mechanical equation, which shows that the resultant cable force acting on the end-effector is directly related to cable length and end-effector pose. A linear expansion of the mechanical equation is carried out to facilitate introducing the mechanical model into the control design, then the relationship between the cable force increment acting on end-effector and the cable length variation and the end-effector displacement is obtained.The cable force on end-effector can be expressed as the addition of its desired value and a corresponding increment resulting from the error of cable length and the error of end-effector pose. In the control design, a feedback controller is first designed for the cable force by using Lyapunov method. Then, by utilizing the above-mentioned incremental relationship,a nonlinear controller based on the end-effector pose feedback is constructed, in which the cable length adjustment quantity serves as the controller for output control. It is essentially a nonlinear PD controller with compensation terms. Controller parameters can be adjusted automatically along with the variation of system state. Numerical examples validate the control algorithm.

Key words:Cable-driven manipulator Dynamics Nonlinear control Trajectory tracking

PP. 17-21

Acceleration Harmonic Cancellation of Electro-hydraulic Servo Shaking Table

YAO Jianjun1HU Shenghai1HAN Junwei2

(1. College of Mechanical and Electrical Engineering,Harbin Engineering University, Harbin 150001, China;2. School of Mechatronic Engineering, Harbin Institute of Technology,Harbin 150001, China)

Abstract:Nonlinearities are inherent in electro-hydraulic servo shaking table. Some nonlinearities are dead zone of servo valve, backlash and friction between joints, and friction in hydraulic cylinder. Nonlinearities cause harmonic distortion of the output acceleration signal corresponding to a sinusoidal input. On the basis of extensive studies on literature related to dead zone, backlash and friction compensation scheme, an adaptive harmonic suppression strategy based on adaptive notch filter technology is proposed. The task is accomplished by generating reference signals with frequency to be suppressed from the output. According to the error between the input acceleration and the feedback acceleration, the weights of filter are adjusted on-line by least mean square adaptive filtering algorithm in real-time. The reference inputs are weighted by the adaptive filter in such a way that it closely matches the harmonic. The output of the adaptive filter is a harmonic replica and is injected to the fundamental signal such that the output harmonic is suppressed, and the total harmonic distortion is greatly reduced. The above course is used as a basis for the development of adaptive harmonic cancellation algorithm.

Key words:Dead-zone Backlash Friction Harmonic suppression Adaptive filtering algorithm

PP. 22-28

Model Parameters Identification Method for Electro-hydraulic Driving Stewart Platform

WU Bo1SHAO Junpeng1WU Shenglin2ZHAO Keding2

(1．College of Mechanical and Power Engineering, Harbin University of Science and Technology, Harbin 150080, China;2．School of Mechatronic Engineering, Harbin Institute of Technology,Harbin 150001, China)

Abstract:Stewart platform driven by electro-hydraulic system is a multi-input and multi-output baroque parallel mechanism, in which serious load-coupling phenomenon occurs between channels. Generally performance parameters of each channel of platfrom are computed or identified according to the theory of servo-valve controlling cylinder system,the results obtained are different from practical operation conditions greatly,which affects the design and performance improvement of the platform control system severely. In order to solve the above problem, a kind of closed-loop identification algorithm of Stewart platform is designed on the basis of Levenberg-Marquardt optimization algorithm and a six-dimension uncorrelated exciting signals, and the experimental research on parameters identification is done on Stewart platform driven by electro-hydraulic test prototype. Experiment results show that the identification algorithm can identify the platform channels performance parameters precisely, and satisfactory identification results are obtained.

Key words:Closed-loop identification algorithm Identification model Stewart platform Electro-hydraulic servo control system

PP. 29-34

4-RUPaR Parallel Robot Mechanisms and Their Kinematics Analysis

CHE Linxian1,2

(1. School of Mechanical & Electrical Engineering, China University of Mining and Technology, Xuzhou 221008, China;2. Institute of Mechatronics Engineering, Luzhou Vocational and Technical College, Luzhou 646005, China)

Abstract:A novel 4-DOF spatial and symmetrical 4-RUPaR parallel robot mechanism that can perform three-dimensional translations and rotation about z axis (3T1R) is presented. The principles that the mechanism can perform the above motions are analyzed by using screw theory, the degree of freedom of the mechanism is calculated, and the rationality of chosen input is discussed. The link-length of the mechanism is taken as the constraint condition to obtain the constraint equations, and nonlinear equations of position analysis are obtained. A unary transcendental equation for positive position analysis of the mechanism is deduced, and the adaptive mutation particle swarm optimization (AMPSO) algorithm is utilized to solve this equation. The closed equation of inverse solution of position and the expressions of velocity and acceleration are deduced. At last, numerical verification of the results of forward and inverse solutions is carried out. The result of forward solution is quite coincident with that of inverse solution. On the basis of the forward position solution analysis, forward solutions of velocity and acceleration of the example are analyzed.

Key words:Parallel robot mechanism Screw theory Forward position solution analysis Kinematics analysis

PP. 35-41

First-order Reliability Method Based Multidisciplinary Design Optimization on Gear Transmission

TONG Lingsheng SHI Boqiang SHEN Yanhua JIANG Yong GUO Pengyan

(Civil & Environment Engineering School, University of Science& Technology Beijing, Beijing 100083, China)

Abstract:Traditional multidisciplinary design optimization (MDO) is a deterministic design method without taking into account the effect of uncertainty factors. In order to reduce the influence of uncertainty on system performance, the first-order reliability method (FORM) is introduced into MDO, and the mathematical model of FORM based collaborative optimization (CO) is set up. The methods of CO and FORM based CO are applied to solving the reliability based MDO for gear transmission of a reducer, and the results of the two methods show that the optimal solution obtained by the FORM based CO satisfies the requirement of reliability. Within the optimization of systematic level of the two methods, the slack variable is introduced to convert consistency equality constraints to non-equality constraints, thus making the algorithm easy to converge. The method of FORM based CO improves the reliability of the gear system, so it has practical engineering significance.

Key words:Multidisciplinary design optimization Collaborative optimization First-order reliability method Gear transmission

PP. 42-46

Time-optimal and Jerk-continuous Trajectory Planning Algorithm for Manipulators

ZHU Shiqiang1LIU Songguo1,2WANG Xuanyin1WANG Huifang1

(1. The State Key Lab of Fluid Power Transmission and Control,Zhejiang University, Hangzhou 310027, China;2. Ningbo Institute of Measurement and Testing,Ningbo 315041, China)

Abstract:In order to optimize the productivity and ensure the running stability of manipulators, a new optimal trajectory planning algorithm is proposed. Position series in joint space are obtained by applying inverse kinematic algorithm to a specified trajectory in task space, and B-splines of seven degree are exploited to interpolate joint position series and generate joint trajectories with continuous velocity, acceleration and jerk,as well as controllable start-stop kinematic parameters. By converting kinematic constraints of manipulators to constraints on control points of B-splines, optimal time nodes are solved by using sequential quadratic programming strategy, then time-optimal and jerk-continuous trajectories which satisfy nonlinear kinematic constraints are planned. Simulating and experimental results show that the proposed trajectory planning algorithm provides ideal trajectories for joint controller, and ensures manipulators to track any specified trajectory in task space stably with the minimum traveling time.

Key words:Manipulator Trajectory planning Optimal execution time Continuous jerk Sequential quadratic programming

PP. 47-52

Design and Test Research of Washout Filter for 6-DOF Platform

DONG Yanliang1XU Caixia2TANG Jianlin1WU Shenglin1

(1. School of Mechatronic Engineering, Harbin Institute of Technology, Harbin l5000l, China;2. Tianjin Electromechanical Industry Holdings Group Corporation Research Institute, Tianjin 300323, China)

Abstract:A large number of modern motion simulators employ 6-DOF platform as motion system. A Washout filter is critical to convert real movement to signals that simulator can simulate since the scope of a simulator is limited. Firstly, a classical Washout filter is designed and the basic form of the filter is confirmed. Two second-order high-pass filters are utilized in the channels of surge and sway. A third-order high-pass filter is used in the heavy direction. Two second-order filters are adopted in surge-tilt coordinate and sway-tilt coordinate channels. Three second-order high-pass filters are applied in the rotary channels. The designed Washout filter is proved to be capable of improving fidelity by simulation. Secondly, a principle of choosing the Washout filter’s natural frequency is concluded by analyzing the correlation between natural frequency and output signal.Finally, the Washout filter is tested on a 6-DOF platform. The experiments demonstrate that the Washout filter reaches the goals of design.

Key words:Washout filter 6-DOF platform Motion simulation

PP. 53-58

Active Disturbances Rejection Vibration Controller Using Extended State Observer and Nonlinear State Error Feedback

CHEN Wenying1,2CHU Fulei1YAN Shaoze1

(1. Department of Precision Instruments and Mechanology,Tsinghua University, Beijing 100084, China;2．Beijing Special Vehicle Research Institute, Beijing 100072, China)

Abstract:Intelligent truss structures, as a new kind of integrated control-structures, have the adaptive geometry and physics characteristics,but these structures also have the complex dynamic characteristics, such as large flexibility, small structure damping, closely low order modes, high degree of mode coupling, uncertainties, and coupling, which brings a great challenge to active vibration control of intelligent truss structures.Therefore, it is studied how to design the model-independent active disturbances rejection vibration controller (ADRVC), based on the extended state observer (ESO) and the nonlinear state error feedback control law (NLSEF). The real-time dynamic linearization of the uncertain nonlinear system is implemented by disturbance estimation via ESO and disturbance compensation via the control law. A NLSEF is designed to control the linear integrator-cascaded type plant. The ADRVC is used for the vibration control of an 83-bar space intelligent truss structure with uncertain-but-bounded parameters. The simulation results demonstrate the ADRVC has good adaptability and robustness to external disturbance and unknown variation in plant parameters.

Key words:Intelligent truss structures Active disturbances rejection control technique Active vibration control

PP. 59-64

Vibration Mode Extraction Method Based on the Characteristics of White Noise

CAO Chongfeng YANG Shixi YANG Jiangxin

(College of Mechanical and Energy Engineering, Zhejiang University,

Hangzhou 310027, China)

Abstract:Focusing on feature extraction in condition monitoring and fault diagnosis of mechanical equipment, a method based on the characteristics of white noise is presented to extract vibration mode from mechanical vibration signal. This method is a developed algorithm of empirical mode decomposition (EMD), which adaptively eliminates high frequency noise components and low frequency false components by applying the characteristics of normalized white noise under EMD, so the intrinsic mode set reflecting actual physical meaning of vibration signal is obtained. Hilbert transform is performed to the extracted intrinsic mode set, and the Hilbert time-frequency feature of observed signals are extracted. In the whole feature extracting process, the construction of general basis function described by some parameters and related filter function is unnecessary, and any prior information about the observed signal is no more required, so the method has a better applicability in actual applications. Both computer simulation and rotor set experimental results verify this approach is feasible and effective.

Key words:Feature extraction Statistical characteristics of white noise Hilbert-Huang transform Vibration mode PP. 65-70

Recognition of Rub-impact Acoustic Emission Signal Based on Fuzzy Entropy

DENG Aidong1ZHAO Li2BAO Yongqiang3

(1. National Engineering Research Center of Turbo-generator Vibration, Southeast University, Nanjing 210096, China;2 . School of Information Science and Engineering,Southeast University, Nanjing 210096, China;3. School of Information Engineering, Nanjing Institute of Technology,Nanjing 210067, China)

Abstract:Fuzzy entropy is used to determine the uncertainty of characteristic parameters of rub-impact acoustic emission (AE) signal in the different rub-impact modes. Average signal level, amplitude, dynamic amplitude range and energies of four nodes reconstruction signals decomposition by wavelet packets are chosen as the characteristic parameters of recognition of AE signal. The membership function of each characteristic parameter belonged to different rub-impact mode based on Gaussian model is obtained from the training samples respectively.Subsequently the fuzzy relation matrix of characteristic parameters and modes is calculated with membership functions. According to different effectiveness in recognizing AE signal by the characteristic parameters, an algorithm based on fuzzy entropy is presented to calculate effectiveness coefficient. The integrated evaluate fuzzy sets is calculated with the new fuzzy relation matrix modified by effectiveness coefficient, and the mode which has the most degree of membership is chosen as the recognition results. The experiments indicate that the integrated fuzzy evaluation is effective in analysis and recognition of AE, and the differences of parameter effectiveness can be used to improve recognition efficiency.

Key words:Acoustic emission Fuzzy entropy Effectiveness coefficient Signal recognition

PP. 71-75

Dynamic Properties of Hub-microbeam System

WU Shengbao ZHANG Dingguo KANG Xin

(School of Sciences, Nanjing University of Science and Technology,Nanjing 210094, China)

Abstract:The dynamic properties of the micro-beam are obviously different from those of the traditional macro-beam due to the size effect of material on a micro scale. The dynamics of a rigid-flexible coupling system consisting of a rotating hub and a flexible micro-beam also known as hub-microbeam system, is studied. The coupling terms of the deformation motion, caused by transverse displacement are taken into account in the deformation displacements of micro-beam. The dynamic characteristic of a micro beam is analyzed theoretically by using couple stress theory (Cosserat theory). The governing equations of motion with the “dynamic stiffening” term and the size effect term for this system are derived by using the Hamilton principle. Based on the obtained dynamic equations, the dependence of the resonant frequency of a micro beam on its size is analyzed. For different rotating speeds, the vibration frequency of the zero order approximate model is compared with that of the coupling model and the suitable range of the zero order approximate model is determined, considering size effect on a micro scale. Finally, the influence of size effect and coupling terms of the deformation motion on the stiffness of micro beam is analyzed. The simulation demonstrates that the resonant frequency of micro-beam increases because of size effect. The influence of size effect is static and that of coupling terms of the deformation motion is related to the rotating speed.

Key words:Rigid-flexible coupling system Micro-beam Resonant frequency Size effect The coupling terms of the deformation motion

PP. 76-82

Dynamical Bifurcation Study on Electromechanical Coupling Vibration in Rolling Mill’s Drive System

LIU Shuang1,2ZHANG Yekuan2LIU Bin2

(1. Key Lab of Industrial Computer Control Engineering of Hebei Province, Yanshan University, Qinhuangdao 066004, China;2. College of Electrical Engineering, Yanshan University,Qinhuangdao 066004, China)

Abstract:In order to solve the problem of low frequency vibration in rolling mill drive system driven by AC motor, the nonlinear dynamics equations of rolling mill drive system with coupling action of electromagnetic energy and mechanical energy are established on the basis of Lagrange-Maxwell theory, and the vibration characteristic of this kind of multidimensional nonlinear autonomous system is studied by using the theory of dynamical bifurcation. Considering the high dimensional bifurcation caused by the nonhyperbolic fixed points when the resistances in stator and rotor change, the nonlinear differential equations’approximate analytical solutions are solved with the aid of multiple time scales and harmonic balance, and the third-order normal form is obtained directly without application of center manifold theory. According to the normal form, the double Hopf bifurcations, 2D tori and 3D tori bifurcations are studied, and the stability of periodic and quasi-periodic solutions is analyzed by using Hurwitz criterion, and the boundary conditions of stable regions are given for each solution. The numerical simulation verifies the correctness of the conclusions, thereby providing a theoretical basis for smooth running of the rolling mill drive system.

Key words:Drive system of rolling mill Electromechanical coupling system Dynamical bifurcation Stability

PP. 83-89

Fault Diagnosis Strategy Based on Complex Network Analysis

DU Haifeng1,2WANG Na2ZHANG Jinhua2SHAO Jie3WANG Sunan2

(1. Center for Public Administration and Complexity Science,Xi’an Jiaotong University, Xi’an 710049, China;2. School of Mechanical Engineering, Xi’an Jiaotong University,Xi’an 710049, China;3. Department of Zoology, University of Oklahoma,Norman 73019, USA)

Abstract:Fault diagnosis, whose essence is pattern recognition of object’s operation state, can be accomplished through clustering methods. The network model is used to represent the fault data structure and thus the clustering problem is converted into the detection task for sub-network structures. Thereby, a fault diagnosis strategy based on complex network structure analysis is proposed. Corresponding to the two central issues for sub-network partition: similarity measure between samples and partition criteria, the modularity concept used broadly in the analysis of community structures in a complex network is introduced into the design of a states differentiating criterion function. To optimize this criterion and accordingly classify fault states, an agglomerative hierarchical clustering algorithm is developed. In applications such as benchmark data classification and four-stage piston compressor diagnosis problem, the effect of similarity measure on algorithm is discussed and the algorithm performance is testified. The comparative results with several artificial intelligent diagnosis algorithms show that the new algorithm can achieve higher diagnosis accuracy, and it is more straightforward, able to extract critical features of the data samples more accurately and therefore accomplishes data clustering with less computational cost.

Key words:Fault diagnosis Clustering Complex network analysis Modularity Compressor

PP. 90-96

Aerodynamic and Aeroacoustic Study on the Cross Flow Fan with Block Stagger Impeller

TIAN Jie1OUYANG Hua1LI You1ZHENG Zhiming2

(1. School of Mechanical Engineering, Shanghai Jiao Tong University,Shanghai 200030, China;2. DAIKIN Industry, Ltd., Osaka 591-8511, Japan)

Abstract:In order to reduce discrete frequency noise of cross flow fan(CFF) of indoor unit of air-conditioner, both aerodynamic and aeroacoustic performance of CFF with block stagger impeller is investigated by using experimental and theoretical method. Four CFF impellers with block stagger angle of 0°, 3.50°, 4.00° and 5.14° are adopted as research objects. It can be shown that the block stagger technique has little influence on the aerodynamic performance of CFF.However, the discrete tone noise levels could be effectively reduced, even though the broadband noise level is also kept constant. Based on the Lighthill’s acoustic analogy theory and Fourier transform character,discrete frequency noise prediction model of CFF is built and used to analyze the influence of different block stagger angles on the discrete frequency noise of CFF. Theoretical analysis results agree well with experimental results. The model can be used to analyze the relationship between stagger angle impeller and BPF noise together with its harmonics of CFF. Meanwhile, the design method of optimum stagger angle of block stagger impeller is also discussed.

Key words:Air-conditioner Cross flow fan Block stagger impeller Discrete frequency noise

PP. 97-102

Electromechanical Analogy Design Theory of Spiral Flywheel Motion Transformation System

LI Chuan1,2DENG Juli1WANG Shilong2ZHANG Xianming1DONG Yutao1

(1. Engineering Research Center for Waste Oil Recovery of Ministry of Education, Chongqing Technology and Business University,Chongqing 400067, China;2. The State Key Laboratory of Mechanical Transmission,Chongqing University, Chongqing 400044, China)

Abstract:A mechanical vibration system with spiral flywheel motion transformation system has merits of lower total mass and better vibration performance. In order to promote its application and reduce integrated design complexity, the dynamical activity of the spiral flywheel is encapsulated with the dynamical analysis. According to traditional force-current electromechanical analogy theory, a novel capacitor component without parallel or grounding constraint is proposed to analogize the spiral flywheel. The component can not only solve the analogy problem for the spiral flywheel, but also perfect the traditional electromechanical analogy theory. The circuit network method is employed so that design steps for the mechanical vibration system based on the spiral flywheel analogy can be presented. In the light of the proposed design theory, the spiral flywheel is applied in a single DOF vibration isolation example for desired performance. Thereby a novel mechanical network and vibration isolation effect that cannot be realized by traditional vibration components are realized. The result shows the effectiveness of the method, which lays a theoretical foundation for integrated design of the spiral flywheel motion transformation system in the mechanical vibration system.

Key words:Motion transformation Spiral flywheel Electromechanical analogy Mechanical vibration Mechanical network

PP. 103-108

Milti-parameter Inversion Technology of Complex Mechanical Product Performance Scheme Design Based on Homotopy Analysis

WEI Zhe1,2FENG Yixiong1TAN Jianrong1LI Zhongkai1

(1. State Key Lab of CAD&CG, Zhejiang University,Hangzhou 310027, China;2. SANY Heavy Equipment Co., Ltd, Shenyang 110044, China)

Abstract:The recording data in the process of development, testing and product prototype running of the complex mechanical product is discrete,making it impossible to accomplish the product performance scheme design effectively. Moreover, there is a large error between the continuous theoretical calculation data and the actual test data. In order to solve this problem, the multi-parameter correlation inversion analysis model is established. By combining the numerical and geometric analysis methods and using multi-parameter correlation homotopy inversion technology, a scheme inversion analysis method to obtain or approximate to the actual continuous parameter data based on the theoretical calculation data and the actual test data is proposed. Using the multi-parameter homotopy revising technology to restrain the observation noise, the performance scheme inversion analysis results are revised, so that the multi-parameter correlation performance scheme design of the complex mechanical product is accomplished. Taking the performance scheme inversion analysis case of the HT××X3Y× series injection molding machine from the Ningbo Haitian Group Ltd. as an example, how this method is applied to the performance scheme design of the practical complex mechanical product is elaborated, and the correctness, effectiveness and practicality of this method is verified in the meanwhile.

Key words:Scheme inversion Homotopy transform Multi-parameter correlation Star coordinates

PP. 109-117

Power Balance Equation about the Numerical Control Machine Tool’s Main Driver System Driven by Variable Voltage Variable Frequency

SHI Jinliang1,2LIU Fei1XU Dijian2XIE Dong2

(1. The State Key Laboratory of Mechanical Transmission,Chongqing University, Chongqing 400044, China;2. School of Electronic and Information Engineering,Chongqing University of Science and Technology,Chongqing 401331, China)

Abstract:In view of the characteristics of energy transmission in the running processes of numerical control (NC) machine tool driven by variable voltage variable frequency (VVVF), an energy flow model of main driving system is established. The power transition characteristics of main motor and mechanical transmission system and the energy loss on every section are analyzed. Finally, the dynamic power balance equation of the whole main drive system is established. Comparing with the equation of common machine tools, this equation has three characteristics.The wide application prospect of the equation is shown by the application analysis and practices.

Key words:Transducer NC machine tool Driving system Power equation

PP. 118-124

Combined B-spline Surface Reconstruction of a Class of Wrap-around Models

SUN Yuwen FENG Xiyou GUO Dongming

(Key Laboratory for Precision and Non-traditional Machining of Ministry of Education, Dalian University of Technology,Dalian 116024, China)

Abstract:For the large wrap-around surface, it is difficult to parameterize the data due to without obvious rectangular boundaries. Meanwhile, the modeling process is inefficient since it involves frequent manual operations. Therefore, a method of combined B-spline surface reconstruction is proposed. First, a method of recognizing the projection axis from sampled points is given, and these points in physical space are projected to two-dimensional space by using the mapping method.Consequently, the boundary curve is divided into four boundary curve segments according to the characteristic of the boundary curve, and then region segmentations and quick parameterizations of points are realized by utilizing Coons surface forms. B-spline surface patches are further reconstructed from segmented point sets. This modeling strategy is very helpful to improving the efficiency and automation of modeling process.In addition, in the process of constructing combined surfaces, a smooth blending method with G1 geometric continuity is provided between two adjacent patches. Examples verify the feasibility and validity of the proposed modeling and blending methods for combined surface reconstruction.

Key words:Wrap-around model Surface reconstruction Combined surfaces B-spline Scattered points

PP. 125-130

Optimization Design of Blade Shapes for Wind Turbines

CHEN Jin1WANG Xudong1SHEN Wenzhong2ZHU Weijun2ZHANG Shiqiang1

(1. The State Key Laboratory of Mechanical Transmission,Chongqing University, Chongqing 400030, China;2. Department of Mechanical Engineering, Technical University of Denmark, Lyngby DK-2800, Denmark)

Abstract:For the optimization design of wind turbines, the new normal and tangential induced factors of wind turbines are given considering the tip loss of the normal and tangential forces based on the blade element momentum theory and traditional aerodynamic model. The cost model of the wind turbines and the optimization design model are developed. In the optimization model, the objective is the minimum cost of energy and the design variables are the chord length, twist angle and the relative thickness.Finally, the optimization is carried out for a 2 MW blade by using this optimization design model. The performance of blades is validated through the comparison and analysis of the results. The reduced cost shows that the optimization model is good enough for the design of wind turbines. The results give a proof for the design and research on the blades of large scale wind turbines and also establish the foundation for further research and industrial application of wind turbines.

Key words:Blades of wind turbines Aerodynamics Cost of energy Optimization design

PP. 131-134

Boundary Surface Straight Fitting Technique with the Constraints of Incomplete Point Cloud

XU Jin1,2KE Yinglin2

(1. School of Mechanical & Automotive Engineering,Zhejiang University of Science & Technology,Hangzhou 310023, China;2. College of Mechanical and Energy Engineering,Zhejiang University, Hangzhou 310027, China)

Abstract:During the process of data acquisition in reverse engineering, the measuring data close to the boundary edges, under the influence of various factors, are sometimes missing. A practical algorithm for boundary surface straight fitting with incomplete point cloud is presented. The base surface is constructed automatically according to its boundary type. The points are projected to the base surface to get the parameters and meanwhile the weakness of each control point is calculated by using a new criterion. The weakly defined control points are constrained and discrete boundary constraints are included during the surface fitting process. The fitting surface is close to the point cloud while preserving good quality of its own.Furthermore, it satisfies approximate G1 continuity with adjacent surfaces.Practical application shows that the proposed algorithm is valid and valuable.

Key words:Point cloud missing Boundary surface Weakly defined control point Surface fitting Reverse engineering

PP. 135-140

Evaluation Method and Application of CNC Machine Tool’s Green Degree Based on Fuzzy-EAHP

WANG Guiping1,2JIA Yazhou2ZHOU Guangwen1

(1. College of Mechanical Engineering, Jilin Teachers’ Institute of Engineering and Technology, Changchun 130052, China;2. College of Mechanical Science and Engineering, Jilin University,Changchun 130025, China)

Abstract:A method applying the fuzzy extension analytic hierarchy process (EAHP) method is proposed to evaluate the green degree of CNC machine tool whose evaluation indexes of green degree can be qualitative and quantitative and multi-hierarchic. It can quantitatively show the relative important degree between indexes with the extension interval number. By the extension interval judging matrix of evaluation index constructed by the experts, the weight of the indexes is identified and the green degree is evaluated step by step with fuzzy synthetic evaluation method. At last the result of synthetical green degree is obtained with fuzzy comprehensive evaluation method. An example with machining center is given to evaluate its green degree. The result shows that the green degree of the machining center is medium. It is consistent with the reality.

Key words:CNC machine tool Green degree Fuzzy comprehensive evaluation Extension analytic hierarchy process

PP. 141-147

Isoparametric and Spiral Toolpath for Free-form Surfaces Machining

XU Jinting1,2,3LIU Weijun1QIU Xiaojie1,2XIA Renbo1

(1. Shenyang Institute of Automation, Chinese Academy of Science,Shenyang 110016, China;2. Graduate University, Chinese Academy of Sciences,Beijing 100049, China;3. School of Automotive Engineering, Dalian University of Technology, Dalian 116024, China)

Abstract:By analysis of the validity of tool path, tool path planning is divided into two processes, the choice of curves on surface and the design of effective and rational path arrangement. On this basis, a spiral topology toolpath for continuous cutfing is developed in order to reduce the number of interruptions and rapid traversals during high-speed machining (HSM)process. Based on the isoparametric toolpath, the contour-parallel isoparametric path is firstly created, and then a spiral path is generated as a kind of diagonal curve between the isoparametric offset curves.Experimental results demonstrate that the proposed method is straightforward and avoids the self-intersection of the toolpath, especially suitable for HSM.

Key words:Free-form surface NC machining Spiral toolpath

PP. 148-151

Cone Crusher Optimization Based on Quality Control and Prediction

DONG Gang1FAN Xiumin1,2HUANG Dongming1

(1. School of Mechanical Engineering, Shanghai Jiao Tong University,Shanghai 200240, China;2. State Key Laboratory of Mechanical System and Vibration,Shanghai Jiao Tong University, Shanghai 200240, China)

Abstract:In view of the solution to the practical problems existing in cone crusher design, the quantity of rock materiel falling out of the crushing chamber during once eccentric rotation of the cone is analyzed,the productivity model for cone crusher with curvilinear chamber geometry is proposed; based on the population balance theory, the division of crushing chamber is analyzed, the product size distribution and corresponding calculation method are researched; combining the empirical model for predicting particle shape with the size distribution model, the flakiness prediction model based on size distribution is proposed. The cone crusher optimization model based on quality control and prediction is built. And the influences of structural and working parameters of cone crusher on productivity and product quality are analyzed. All these tasks are useful for future cone crusher optimization strategies.

Key words:Cone crusher Optimization model Productivity Size distribution Flakiness index Quality control and prediction

PP. 152-157

Case-based Reasoning Approach for Cutterhead Principal Parameter Design of Full Face Rock Tunnel Boring Machine

LIU Zhijie1,2SHI Yanjun1TENG Hongfei1

(1. School of Mechanical Engineering, Dalian University of Technology, Dalian 116024, China;2. Transportation & Logistics Engineering College,Dalian Maritime University, Dalian 116026, China)

Abstract:The cutterhead principal parameter design is one of the key issues of full face rock tunnel boring machine (TBM) and is a crucial factor in influencing the performance of TBM. The mechanism of cutterhead cutting rock is complex and the cutterhead needs to be adaptable and designed for specific rock characteristics. Therefore, it is necessary to make full use of successful experiences and data accumulated in TBM cutterhead design. A case-based reasoning approach is proposed for TBM cutterhead principal parameter design. The representation of cutterhead design case is given. According to the characteristics of local attributes in each case, the calculation method of local similarities are provided correspondingly. For the local attribute whose value is at interval,an interval similarity calculation method is presented on the basis of attribute value probability distribution in the interval range. A combined case modification method is used to obtain the final solution of the new design issue. The application of an engineering case shows the design results with the proposed method are better.

Key words:Full face rock tunnel boring machine Cutterhead principal parameter design Case-based reasoning Similarity Combined case modification

PP. 158-164

Simulation and Experimental Study on Photoresist Flow and Deforming Behavior in Imprint Lithography Process

WANG Quandai1DUAN Yugang1LU Bingheng1LI Dichen1XIANG Jiawei2

(1. State Key Laboratory for Manufacturing Systems Engineering,Xi’an Jiaotong University, Xi’an 710049, China;2. School of Mechanical & Electrical Engineering,Guilin University of Electronic Technology, Guilin 541004, China)

Abstract:It is necessary to understand and predict the photoresist flow and filling behavior in imprint lithography process to obtain high fidelity replication of the template patterns. The finite element model based on viscosity fluid for resist flow and filling is established considering the properties of the resist adopted in this study and the influences of geometric characteristics of template patterns, initial resist film thickness and micro/nano effect on resist rheologic properties are investigated to distinguish different flow driving mechanisms by tracing the resist moving boundary by using volume of fluid (VOF) method. The calculation results show that the resist filling is accomplished in single or dual peak deformation mode. The mode transition point can be predicted from the ratio of characteristic groove width to initial resist film thickness and the transition point is influenced by the surface/interface effects. The required from pressure is minimized when the aspect ratio of the template patterns is approximately 0.8. The optimal initial resist thickness is about twice of the depth of the patterns on the template considering both the pattern transfer quality and residual resist thickness. The numerical simulations are compared with the related experimental results in imprint lithography and it shows that the calculation results are in good agreement with the experimental results, which indicates that the conclusions from simulation analysis are valid and can be used as the process layout rules for the template pattern geometry, initial resist thickness and template surface treatment.

Key words:Imprint lithography Rheological analysis Volume of fluid method Numerical simulation

PP. 165-171

Experiment Study on Machining Array Micro-pits in Electrochemical Machining Method with a Mask onto the Cathode

DU Haitao1QU Ningsong1,2LI Hansong1,2QIAN Shuangqing1

(1. College of Mechanical and Electrical Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 210016, China;2. Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology, Nanjing University of Aeronautics and Astronautics,Nanjing 210016, China)

Abstract:To obtain micro-pits array which can reduce friction and wear of friction pairs, an electrochemical machining method with a mask onto the cathode is proposed to produce the micro-pit array patterns. Finite element simulation of the method is carried out to analyze the effect of the photoresist thickness on the pit size and shape. The experiments of micro-ECM are done to analyze the effect of frequency and duty cycle on the diameter of micro-pits, in which the cathode plate with the hole diameter of 100 μm is produced by using lithography method. The experimenter’s result reveals that the micro-pits with the diameter of 200 μm and the depth of 10 μm can be obtained in electrochemical machining method with a mask onto the cathode.

Key words:Photoresist Micro-ECM Array micro-pits

PP. 172-178

Ultrosonic Combined Electrical Micro-machining Technology and Its Application

ZHU Yongwei WANG Zhanhe FAN Zhongjun TAO Jiansong ZHANG Lei

(College of Mechanical Engineering, Yangzhou University,Yangzhou 225009, China)

Abstract:The ultrasonic combined electrical micro-machining new technology is advanced for manufacturing micro-instruments and micro-structures. The ultrasonic combined electrical micro-machining systems with machining parameters adjustable in a wide range are built and improved. The micro-machining mechanism is analyzed and discussed.Micro-tool electrodes in different sections and sizes that can meet testing and actual machining requirements are manufactured by combined electrical discharge micro-machining. Multi-parameter ultrasonic combined electrical micro-machining tests are carried out. The results show that the ultrasonic combined electrical micro-machining new technology has the advantages of high machining efficiency and accuracy and low cost. This technology is used to manufacture friction pair surface lubricant retention micro-structures.The friction tests prove that the lubricant retention micro-structures can reduce friction coefficient and wear of friction pair surfaces.

Key words:Ultrosonical machining Combined electrical-machining Micro electrode Micro-structures manufacturing Friction and wear

PP. 179-186

Model of Side Contact Layer and Wear Performance of CBN Wheel in Quick-point Grinding Process

XIU Shichao CAI Guangqi

(School of Mechanical Engineering & Automation,Northeastern University, Shenyang 110004, China)

Abstract:Based on the principle and technical characteristcs of point grinding process, the function of the side contact area of the thin CBN point-grinding wheel in material removal process is discussed, and the geometry and parameters models of the side contact area are established.Mathematic modeling and analysis are carried out for the side contact layer parameters, such as the equivalent workpiece diameter, the geometric and dynamic contact arc length, cutting depth of single abrasive grain and average cross-sectional area of chips. The grinding experiment is carried out to study the mechanism of effect of side contact layer parameters on the quick point grinding process and the wear characteristic and rule of thin CBN point-grinding wheel. It is found that the material removal is mainly completed in the side contact layer and the maximum wear rate of the thin CBN point-grinding wheel occurs at the largest circumference of wheel side in the point grinding process.

Key words:Quick-point grinding Side contact layer Model Grinding experiment Grinding wheel wear

PP. 187-192

Research on Reconstruction and Recursion Interpolation of Curve with High-speed and High-precision

SHI Qun YOU Qingning HUANG Yuliang GAO Shenglin

(School of Mechatronics and Automation, Shanghai University,Shanghai 200072, China)

Abstract:Aiming at low recursion-rate and poor approximation accuracy of polynomial-basis Hermite curve, which is commonly used in real-time interpolation of middle and top grade computer numerical control(CNC), a new kind of splines based on algebraic-exponential space, which takes full advantage of high recursion-rate and convergence-rate of exponential function e–t, is reconstructed. The experiment shows that the recursion rate of new curve is 1.7～2.1 times that of Hermite curve, and at the same time,the approximation precision is improved by one order of magnitude. The result indicates that the interpolation-algorithm based on new curve not only promotes machining precision of profile, but also improves machining efficiency simultaneously, thereby meeting the construction requirement of spline curve in middle and top grade CNC.

Key words:Computer numerical control High speed and high precision Spline interpolation Algebraic-exponential spline basis High-speed recursion

PP. 193-198

Vol. 46, No. 4, 2010

Patch Near-field Acoustic Holography by Extrapolation Using Orthogonal Spherical Wave Source

XU Liang BI Chuanxing CHEN Xinzhao WANG Hui

(Institute of Sound & Vibration Research, Hefei University of Technology, Hefei 230009, China)

Abstract:In order to reduce the reconstructed errors, the near-field acoustic holography requires the measurement aperture larger than the sound source area. This limitation causes heavy measurement work and makes the NAH difficult to implement on large-scale structure. To solve this problem Patch near-field acoustic holography based on hologram pressure extrapolation is developed. A new patch near-field acoustic holography (PNAH) based on exploration using orthogonal spherical wave source is proposed. According to the solution of Helmholtz equation in spherical coordinates, the sound field can be approximately expressed as a linear sum of a series of orthogonal spherical wave function, so that the sound field generated by vibrator is approximated by superposing fields generated by a series of orthogonal spherical wave sources of different orders and the pressure exploration is realized by radiating process of these spherical wave sources. After near-field exploration the fast Fourier transform (FFT) method is implemented for reconstructing the normal velocity or the field on and near the radiator. The results of numerical simulations show that the method can work well in the small measurement aperture, reduce the requirement of measurement aperture area, and is convenient for application.

Key words:Near-field acoustic holography Extrapolation Orthogonal spherical wave

PP. 1-7

Effects of Piezoelectric Ceramic on the Stator Performances of Ultrasonic Motor

WANG Guangqing1SHEN Runjie2GUO Jifeng2

(1. College of Information & Electronics Engineering,Zhejiang Gongshang University, Hangzhou 310018, China;2. College of Electrical Engineering, Zhejiang University,Hangzhou 310027, China)

Abstract:The piezoelectric ceramic(PZT) is one of the key elements of the ultrasonic motor stator, its performance greatly affects the output characteristics of the ultrasonic motor. In order to research the effects of PZT on the output characteristics of ultrasonic motor, the electromechanical coupling dynamics model of the free stator is built by using finite element method . Based on the model, the effects of the thickness, polarization partition format and polarization inhomogeneity of the PZT on the stator dynamic performance are studied. And the energy evaluation method of the effects of the PZT on the stator dynamic characteristics is proposed. Meanwhile, The theoretical model of temperature characteristics of the ultrasonic motor stator is built by using Newton cooling law and heat capacity theory. Based on the model, the effect of dielectric loss of PZT material on the temperature characteristics of the stator is researched. The results show that the stator modal frequency increases with the enhancement of PZT thickness, while the vibration amplitude of the stator surface particle decreases with the increase of PZT thickness. Meanwhile, the stator modal frequency when PZT is in open circuit condition is greater than that when PZT is in short circuit condition. Based on the research results, a prototype of traveling-wave type ultrasonic motor with 10.4 mm diameter is produced,experiments show that the maximum torque of the motor is 9.5 mN·m, the no-load speed is about 1 000 r/min. The research results are helpful to the industrialization of the ultrasonic motor.

Key words:Ultrasonic motor Piezoelectric ceramic Stator performances Finite element model Energy Temperature

PP. 8-14

Magnetic Memory Experiment Based on Magnetic Gradient Measurement

JIAN Xingliang1ZHOU Keyin2

(1. College of Engineering, Nanjing Agricultural University,Nanjing 210031, China;2. College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China)

Abstract:Metal magnetic memory technology is a new nondestructive testing method. To explore a new diagnostic method based on magnetic gradient testing, a series of tensile tests on low carbon steel bars are carried out in geomagnetic field environment. A self-made special detector is used to measure the magnetic gradient above the material surface. The results show that the relation between the magnetic gradient and the stress varies with different measurement methods. The magnetic gradient has no specific relation to tensile stress if the sample is placed on the tensile testing machine and measured. If the sample is taken off from the machine and measured, the magnetic gradient shows a linear relation with the maximum stress that the sample was subjected to recently. It offers a new method for nondestructive measurement of stress by measuring the magnetic gradient on the ferromagnetic component surface. In addition,magnetic memory signal will gradually decrease after the sample is taken off and laid aside, which shows that the detection of stress concentration by using metal magnetic memory technique is time dependent.

Key words:Magnetic memory testing Magnetic gradient Stress concentration Neck contraction

PP. 15-21

Investigations on CFRP Porosity by Using Ultrasonic Testing Based on Random Pores Model

MU Yunfei1ZHANG Xiang1LIN Li1TIAN Hongtao1GUO Guangping2LI Ximeng1

(1. NDT & E Laboratory, Dalian University of Technology,Dalian 116024, China;2. Beijing Institute of Aeronautical Materials, Beijing 100095, China)

Abstract:In order to solve the problem that there are differences between the analytical and experimental results of ultrasonic testing of carbon fiber reinforced plastics (CFRP) porosity by using ultrasonic attenuation method, a mathematical characterization for pores in CFRP is proposed on the basis of random medium theory. Random medium with ellipsoidal autocorrelation functions is improved through minimum searching method.The effects of building parameters are found with orthogonal test. And parameters such as autocorrelation length a and b, ratio of autocorrelation length r0=a/b and side length of sub-zone D, are optimized according to a large number of CFRP pores morphology and distribution statistical data.Finally, random pores model for CFRP is established. The results show that the morphology and distribution of pores can be characterized by random pores model based on actual statistical data of pores, which provides the theoretical foundations for the analysis of ultrasonic scattering from CFRP pores. For the relation between ultrasonic attenuation coefficient and porosity, the result of numerical calculation accords with that of experimental test. The result shows that random pores model can characterize global elastic properties and partial elastic disturbance from random pores of CFRP.

Key words:Carbon fiber reinforced plastics Porosity Random medium Random pores model

PP. 22-26

Compliance Process Analysis for Forging Manipulator

ZHAO Kai1WANG Hao1CHEN Guanlong1LIN Zhongqin1HE Yongbo2

(1. School of Mechanical Engineering, Shanghai Jiao Tong University,Shanghai 200240, China;2．Special Steel Branch, Baosteel Co. Ltd., Shanghai 200940, China)

Abstract:A multi-domain dynamic modeling of forging manipulator including forging, mechanism and hydraulic elements is established to study a forging process. Based on the modular approach, the forging subsystem, mechanism subsystem and hydraulic subsystem are all expressed in state space equations, which can form the coupling dynamic model by defining the input and output relations among subsystems. The model is utilized to describe and analyze the compliance process and the characteristics for two periods of compliance are revealed, that is: two degrees of freedom active compliance stage and three degrees of freedom active and passive compliance stage. The compliance process under one typical working condition is simulated and analyzed based on three different cases: invalidation of buffering cylinder, constant pressure of buffering cylinder and the actual situation. The simulation results show that the compliance movement will on one hand protect the manipulator from being damaged by large load and on the other hand improve the external load environment, which has great significance to keep the manipulator work in good conditions. The theoretical basement is also provided for the design and optimization of forging manipulator.

Key words:Manipulator Compliance Dynamics Forging

PP. 27-34

Numerical Simulation and Virtual Failure of Particle Reinforced Composite Microstructure

REN Huaihui LI Xudong LI Junchen

(State Key Laboratory of Advanced Non-ferrous Material,Lanzhou University of Technology, Lanzhou 730050, China)

Abstract:Samples of particle reinforced composite microstructures generated by material microstructure simulation software ProDesign,including a large number of Voronoi grains and ellipsoidal particles, are used to simulate real-composite material microstructures, to study the influence of anisotropy and locality on mechanical properties of the composite microstructures. Micro-stress numerical calculation of particle reinforced composite microstructures is achieved by secondary development of the commercial finite element software ABAQUS, and computer simulation experiments confirm that the mismatching of stiffness of the particles and the matrix material, and local anisotropy of the orientation of microstructure components, play a decisive role in the distribution of the composite material structural weaknesses. On the basis of the results, the numerical response of micromechanics of microstructure achieved by finite-element method is of great significance to identify“material structure weakness”, evaluate initiation and propagation of microcracks of microstructures for heterogeneous materials, predict material performance after material microstructure damaging, deduce the“virtual failure behavior” of microstructure.

Key words:Material microstructure Numerical simulation Material structure weakness Virtual failure Anisotropy

PP. 35-41

Numerical Analysis of Dynamic Surface-deformation of Fully-penetrated Gas Tungsten Arc Welding Molten Pool

ZHAO Ming QIN Yawei SUN Yongxing

(College of Mechanical & Electronic Engineering, China University of Petroleum, Qingdao 266555, China)

Abstract:Based on the principles of energy and mass conservation as well as energy minimization theory within a whole system of fully-penetrated gas tungsten arc welding (GTAW) molten pool, the governing equations are derived to describe the pool surface-deformation on both sides. The solution scheme for determining the Lagrange parameter is given for the coupled upper and bottom pool surface-deformation equations which are unified with a single Lagrange parameter. Through predicting and analyzing the dynamic variation processes of both upper and bottom pool surface-deformation during the period from the weld pool formation to its quasi-steady state for GTAW stainless steel and low carbon steel, the variables are extracted to characterize and judge the condition whether the workpiece is penetrated or not. It lays foundation for realizing welds penetration control based on front-side vision inspection.

Key words:Weld pool surface-deformation Lagrange parameter Penetration control Numerical analysis

PP. 42-47

Numerical Simulation of Square Box Part Deep Drawing Process by Using Mesh-free

LIU Hongsheng1XING Zhongwen1YANG Yuying2

(1. School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China;2. School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China)

Abstract:A new type of numerical method called mesh-free method is presented to implement the simulation of square box part deep drawing in view of the drawback of finite element method. Mechanics equations for dominating the sheet metal forming process based on mesh-free reproducing kernel particle method are developed. The material shape function is adopted to avoid the frequent updates of shape function and influence domain. To impose the essential boundary conditions exactly,mesh-free shape function is re-constructed and the modified shape function called kinematically admissible shape function is interpolatory.The all shape functions associated with nodes within the whole domain are re-constructed in order to enforce the complex essential boundary conditions expediently and exactly. The nodes distributed in the die are used to construct a matrix owning the characteristic which can be used to search the slave node being in contact with the die. Furthermore a data structure called “sparse matrix” is proposed to accelerate the contact searching. The program for simulating the sheet metal forming process is set up, and the mesh-free simulations of deep drawing for the square box part are implemented. The influence of blank holder force on the deep drawing is investigated, and the distributions of thickness, stress and strain are obtained by meshless numerical simulations. The comparison of numerical results with experimental results shows the effectiveness of using mesh-free method to simulate sheet metal forming.

Key words:Numerical simulation Finite element method Stamping Mesh-free method

PP. 48-53

Study on Manufacture Process and Mechanical Property of Crusher Ring-hammer

LI Shifeng1GAN Yusheng1LI Yongtang1LI Zhengwei2SONG Jianli1

(1. College of Material Science and Engineering, Taiyuan University of Science and Technology, Taiyuan 030024, China;2. Shanxi Equipment Factory of Electric Power,Taiyuan 030024, China)

Abstract:In view of the weakness of ring-hammer such as cracks,breakages, poor wear resistance and short service lifet, a high wear-resistant steel with initial hardness up to HB 210 and impact ductility above 215 J·cm–2is developed successfully, which is based on the high manganese steel with the addition of alloy agents and composite modification, by designing component, designing processes which include a new lost foam casting process of iron-sand molding & spiral-ring chill and a heat treatment for precipitation strengthening. The results show that after multi-element microalloying and composite modification, second hard phase particles such as alloy carbides are formed and dispersively distributed in the austenitic matrix, thereby strengthening the matrix and improving the initial hardness of material. When iron sand is adopted for molding, it not only has the inherent characteristic of molding sand but also plays the function of metal mold, so that the grains of casting are refined , and the microstructure density is improved. The production practice shows that the properties of the ring-hammer produced on the basis of such technique can be obtained as follows: tensile strength σb=724 MPa, impact toughness αk=219 J·cm–2, percentage elongation δ =37%,Brinell hardness 210 HB respectively after precipitation strengthening treatment by water quenching at 1 080 ℃ for 4 h and tempering at 320 ℃ for 3 h, which can meet the application requirements, the products have good wear-resistant property in practical application and obvious market competitive advantage.

Key words:Crusher ring-hammer Multi-element micro-alloying Composite modification Lost foam casting of iron-sand molding Precipitation strengthening process

PP. 54-59

Signal Processing of All-digital Inverter Welder Based on Wavelet

DUAN Bin SUN Tongjing LI Zhenhua ZHANG Guangxian MEI Gaoqing

(College of Control Science and Engineering,University of Shandong, Jinan 250061, China)

Abstract:The working environment of inverter power sources is filled with strong interference, high voltage and current. To obtain useful signals of the inverter welding machine from harsh environment is the key to R&D and technological evaluation of all-digital welding power source. A new method is put forward after analysis and research on the principle of pulse width modulation (PWM) driving, i.e. the current signal of inverter welding machine at PWM driving level is denoised first, then noise filtering of the whole welding current signal is carried out. Hard threshold function is constructed to carry out wavelet decomposition of signal, and the detail coefficients are denoised. At the same time, modulus maxima discriminant function is constructed to search noise singular points from detail coefficients. The search results are used to denoise approximation coefficients linearly. Simulation experiments based on selection of appropriate correlation parameters show that the method can filter welding current noise effectively, ensure distortion-free signal and obtain useful signal characteristics, thereby laying the foundation for the research and performance evaluation of all-digital inverter power source.

Key words:All digital inverter Wavelet transform Modulus maxima Threshold Performance evaluation

PP. 60-64

Analytical Closed Form Solution of Load-displacement Curve for Cracked Plates Considering Thickness Effect of Resistance Curve

WU Jianguo WANG Qizhi ZHANG Xing

(School of Aeronautical Science and Engineering, Beihang University,Beijing 100191, China)

Abstract:At present, accurate prediction of residual strength of long lifetime structure during its service period is an important and difficult problem facing the structural design engineer. A precise load-displacement curve in the process of crack growth will provide a highly effective solution to this problem. For that, based on the fracture toughness and resistance curve theories with thickness effect considered, an investigation of load-displacement curve for a plate with growing crack is made from both theoretical and experimental aspects. An expression is given by the Castigliano’s theorem to show the relation between the external loads and the deflection on the midpoint of specimen with a stationary crack. The fracture toughness and resistance curve theories with thickness effect considered are introduced to educe the analytic closed form solution to load-displacement curve at the midpoint of specimen during crack growth. A few experiments of crack growth are also performed under monotonously quasi-static loading. The experimental data are basically consistent with the results from the analytical closed form solution, which confirms the validity of this analytical closed form solution sufficiently.

Key words:Crack growth Load-displacement curve Thickness effect Analytical closed form solution

PP. 65-73

Experimental Research on the Dynamic Constitutive Relation of Pure Iron at Elevated Temperatures and High Strain Rates

BAO Weiping1ZHAO Yuzhen1,2LI Chunming3REN Xueping1

(1. School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083, China;2. Shanxi Taigang Stainless Steel Co. Ltd., Taiyuan 030003, China;3. WISDRI Engineering and Research Incorporation Ltd.,Wuhan 430223, China)

Abstract:The experiment of dynamic mechanical behaviors test of pure iron is carried out at wide temperatures range (293～1 073 K) and high strain rates (2 000～8 500 s–1) with split Hopkinson pressure bar, which is installed with heating device and synchro assembly system. The stress-strain curves of material under temperature-strain rate coupling actions are obtained. The mechanism of effect of temperature and strain rate on the plastic flow stress of pure iron is discussed. The studies show that the pure iron has evident heat softening effect, strain rate strengthening effect and strain hardening effect, and flow stress increases with temperature decreasing and strain rate increasing. The Johnson-Cook constitutive model that is fitted by stress-strain curves obtained from experiments can provide satisfactory prediction of the plastic flow stress of pure iron.

Key words:Pure iron Stress-strain curve High strain rate Flow stress Johnson-Cook constitutive model

PP. 74-79

Fuel Optimal Control of CVT Equipped Vehicles with Consideration of CVT Efficiency

LUO Yong SUN Dongye QIN Datong CHEN Ran HU Fengbin

(The State Key Laboratory of Mechanical Transmission,Chongqing University, Chongqing 400044, China)

Abstract:Conventionally, continuously variable transmission (CVT)improves fuel economy by ensuring the engine works under a high efficiency condition. However, this method does not pay any attention to the CVT efficiency. The CVT efficiency changes from 70% to 95% with its work condition, which also has considerable influences on fuel consumption of the system. Based on the analysis of how CVT efficiency and engine efficiency influence the fuel consumption of the system, an optimal economy control method with consideration of both engine and CVT efficiency is proposed. An optimal algorithm is proposed to calculate the combinations between the engine torque and CVT ratio in order to achieve the highest overall efficiency of engine and transmission system.A simulation model is built to validate the optimal algorithm. Experiment under several static vehicle speeds are also carried out to validate the control method. Simulation and experiment results indicate that fuel consumption of the system is reduced by more than two percent after the optimization.

Key words:Continuously variable transmission Efficiency Optimal economy control

PP. 80-86

Influence of Air Pressure Pulse on Side Windows of High-speed Trains Passing Each Other

LI Renxian1,2ZHAO Jing1LIU Jie1ZHANG Weihua2

(1. School of Mechanical Engineering, Southwest Jiaotong University,Chengdu 610031, China;2. Traction Power State Key Laboratory, Southwest Jiaotong University, Chengdu 610031, China)

Abstract:Air pressure pulse from high-speed trains passing each other will cause a big impact on train side windows，which could result in a broken window accident, thereby bringing about hidden danger to passengers and train running. Based on 3D, Reynolds average Navier-Stokes equations of viscous fluid and k-ε two equations turbulent model, dynamic processes of high-speed trains passing each other in open air and in long tunnel at five different speeds (200, 250, 300, 350 and 400 km/h) are simulated and analyzed by using moving mesh finite volume method. Complete pressure pulse change profile on side windows is obtained. The calculation results show that there is a big difference between pressure pulses from trains passing each other in open air and in long tunnel. Minus pressure pulse peak acting on train side windows as the trains passing through each other in long tunnel is about two times that in open air. Therefore it is not correct to using the pressure pulse change tendency of trains passing through each other in open air to that in tunnel.Based on the results of calculation, reasons of side window broken from trains passing through each other and the method of assessment for side window strength are analyzed. When side windows of a high-speed train are designed, not only the strength of resistance to impact on window glass should be considered, but also assembling strength of the window glass must be considered. A glass window with long perimeter is favorable for resistance to impact of air pressure pulse when the windows aera equal.

Key words:High-speed train Pressure pulse from trains passing each other Side windows

PP. 87-92

Dynamic Characteristics Fitting of Air Springs and Numerical Analysis of Air Suspensions with Variant Stiffness

CHEN Liao ZHOU Kongkang LI Zhongxing

(School of Automobile and Traffic Engineering, Jiangsu University,Zhenjiang 212013, China)

Abstract:For studying vehicle air suspension more accurately, the variant stiffness of air springs should be considered in the process of building dynamic models of vehicle suspension and simulation of the models.Based on the test data of dynamic characteristics of air spring, the numerical stiffness equations of air springs used in the air suspension of vehicle are obtained by means of nonlinear curve fitting according to the loads and equilibrium heights of air springs. In the beginning of every simulation step of discrete state space model of half vehicle, the value of air spring stiffness is changed and determined according to the dynamic deflection value of the suspension. In comparison with the experimental air spring pressures during the suspension step tests, the pressure difference between calculation and test is reduced greatly, which shows the effectiveness of the proposed method of dynamic characteristics fitting of air spring and nonlinear simulation of suspension models.

Key words:Vehicle Air suspension Air spring Stiffness Simulation Curve fitting

PP. 93-98

Analysis of Flow and Heat Transfer in Novel Evaporator of Miniature Flat Plate Capillary Pumped Loop

WAN Zhongmin1,2LIU Wei2MING Tingzhen2LIU Zhichun2

(1. Department of Physics, Hunan Institute of Science and Technology,Yueyang 414006, China;2. School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China)

Abstract:A novel evaporator of miniature flat plate capillary pumped loop (CPL) is presented for application of dissipating high heat flux.Based on the structure characteristics of miniature flat plate CPL evaporator, the effect of metal side wall conduction of evaporator on the CPL work limit is analyzed. An overall numerical model for the miniature flat plate CPL evaporator is presented, which includes heat and mass transfer in the porous wick structure, liquid flow and heat transfer in the compensation cavity and heat transfer in the vapor grooves and metallic wall. The entire evaporator is solved with SIMPLE algorithm as a conjugate problem. The numerical results show that liquid evaporation takes place near the upper and left surfaces of wick structure in the evaporator. The flat plate evaporator with single aluminum wall results in lower heat transfer limit, but leads to low temperature level and good isothermal behavior of the heated surface. On the other hand, the evaporator with single stainless steel wall leads to higher heat transport capacity, but to higher temperature level of the heated surface. The evaporator with combined wall (upper wall with aluminum, side and bottom wall with stainless steel) increases heat transfer limit, and decreases temperature level and temperature gradient on the heated surface, which implies that the CPL can operate safely and cooled apparatus also can work effectively under high heat fluxes.

Key words:Capillary pumped loop Evaporator Porous media Coupling computation

PP. 99-104

Experimental Study on Combustion and NOx Emission Characteristic of 1 000 MW Ultra-supercritical Coal-fired Boiler

HU Zhihong1HAO Weidong1XUE Meisheng2WANG Jun3

(1. Department of Thermal Engineering, Shandong Electrical Power Research Institute, Jinan 250002, China;2. Department of Automatism, University of Science and Technology of China, Hefei 230026, China;3. Boiler Research Institute, Dongfang Boiler (Group) Co. Ltd.,Zigong 643001, China)

Abstract:For getting higher efficiency and lower NOxemission, a test to optimize combustion system is conducted in a 1 000 MW bituminous coal-fired boiler in opposed firing pattern. During the test, the gas temperature distribution in furnace is measured, combustion and NOxemission characteristic is studied by varying such factors as type of coal,O2at economizer exit, mass flow of over fired air (OFA), air damper position of burner and after air port (AAP), combinations of burners and boiler load. It indicates that O2at economizer exit and mass flow of OFA have great effect on boiler efficiency and NOxemission. It’s better to keep these two parameters at 3.0% and 750 t/h respectively , which can also eliminate slagging on platen superheater. O2deviation along furnace width can be eliminated by setting outer second air damper of burners in same horizontal row at different proper positions. Unburned carbon in fly ash can be decreased by using design coal, closing outer second air damper of AAP, setting burner’s core air damper at 50% and shutting down one-layer upper row burners at full load if possible. After adjustment, the measured efficiency of boiler is above 94.4% and NOxemission concentration is lower than 300 mg/m3. They are obviously better than those of boilers in service in China.

Key words:Ultra-supercritical Coal-fired boiler Opposed firing NOxemission

PP. 105-110

Blade Stress of the Reactor Coolant Pump of 300 MWe Nuclear Power Plant in China Based on Fluid-solid Coupling Method

CHEN Xiangyang YUAN Danqing YANG Minguan YUAN Shouqi

(School of Energy and Power Engineering, Jiangsu University,Zhenjiang 212013, China)

Abstract:In order to compute and analyze the blade stress in reactor coolant pump of a 300 MWe nuclear power plant in China , from the viewpoint of safety performance, the fluid-solid coupling technique is adopted to solve the fluid and solid coupling equation. Theoretical analysis shows that the blade stresses mainly include tensile stress caused by centrifugal force, bending and torsional stresses induced by flow-field pressure, and thermal stress brought by temperature field. From the analysis results, it is concluded that the max equivalent (Von-Mises) stress exists in fixed supports and the blade stress does not have strict periodicity,and the disordered distributions of blade stress lies in the complex internal flow. The differences between impeller and guide vane are proved by comparison of theory and simulation and the main factors are explained.Lastly the intensity examination proves that the intensity of the reactor coolant pump meets the requirement of ASME. This could be used for improving aerofoil design and ensuring performance and intensity.

Key words:Reactor coolant pump Fluid-solid coupling Equivalent(Von-Mises) stress Intensity examination

PP. 111-115

Investigation on Aerodynamic Similitude for Axial Microfan

WANG Qikun CHEN Kangmin

(College of Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China)

Abstract:Axial microfan is widely used as cooling equipment for electronic devices such as PCs. Currently, the PC size becomes smaller and smaller while their operating speed becomes faster and faster, which calls for better cooling performance of axial microfan. As an important and effective design approach, the similitude design has been widely used in the design of large and medium fans, but not yet in the design of axial microfan. One main reason is that the flow inside the microfan is located in non self-similitude area for Reynolds number, which results in the poor performance of the microfan designed by those similitude criterions that are surely effective for the design of fans, where the flow is located in self-similitude area for Reynolds number. By using the similitude principle for aerodynamics, the aerodynamic similitude conditions for axial microfan are proposed. Compared to 错误！链接无效。fans in self-similitude area, a new criterion called ‘chord Reynolds number’ is proposed and is numerically validated with the discussions on its applicability and limitation. Results indicate that ‘chord Reynolds number’can well realize the aerodynamic similitude for the axial microfan but it requires that the revolution speed of the impeller should be in direct proportion to the square of the reduced scale, so the reduced scale of model impeller shall not be too large, otherwise new non similitude factors may occur again due to too high revolution speed

Key words:Similitude criterion Aerodynamic performance Axial microfan

PP. 116-121

Analysis of Cavitation and Flow Computation of Inducer

GUO Xiaomei1,2ZHU Zuchao1,3CUI Baoling1LI Yi1

(1. Laboratory of Fluid Power Transmission, Zhejiang Sci-Tech University, Hangzhou 310018, China;2. Department of Electrical and Mechanical, Zhejiang Water Conservancy and Hydropower College, Hangzhou 310018, China;3. The State Key Lab of Fluid Power Transmission and Control,Zhejiang University, Hangzhou 310027, China)

Abstract:In order to obtain the distributions of velocity, pressure and turbulence in inducers, on the basis of SIMPLEC algorithm, the 3D turbulent flow in inducers of two structures is numerically computed by using the time-averaged N-S equation and the modified k-ε turbulent model. The calculation result proves that the outer margin near the inlet is where cavitation damage most easily takes place. The result also shows that increasing the lead and the axial length of inducer can improve the suction performance. The performance of cavitation tests in the centrifugal pump with an inducer of two different structural parameters and without an inducer are carried out. The result shows that the pump is easy to have cavitation without the inducer, and the cavitation performance can be improved by adding inducer. The parameters of inducer lead, axial length and the blade angle will influence the cavitation performance. Results of numerical calculation and experimental research proves that increasing the lead and the axial length of inducer can improve the suction performance.

Key words:Centrifugal pump Inducer Numerical calculation Suction performance

PP. 122-128

Energy Characteristic State Model of Hydraulic System Conceptual Design

MA Wenyong WANG Delun

(School of Mechanical Engineering, Dalian University of Technology,Dalian 116024, China)

Abstract:An energy characteristic state model for hydraulic system conceptual design is presented. The energy characteristics of hydraulic systems are represented by qualitative vectors, and integral hydraulic systems are visualized as several single-action subsystems for design.Basic transformation units are defined as new design building blocks from general hydraulic components, and the qualitative matrix representations for these design building blocks are established according to the function analysis. A conceptual design model of single-action system is developed,in which the conceptual design of single-action subsystems are transformed into the decomposition of system-level matrices and the matching of candidate matrices of basic transformation units. A design example is also given to show the feasibility and effectiveness of the approach.

Key words:Conceptual design Hydraulic system Energy characteristic state CAD

PP. 129-135

Analysis and Design of Energy Regulation Device in Energy Regulation Based Variable Speed Electro-hydraulic Control System

XU Ming JIN Bo SHEN Haikuo LI Wei

(The State Key Lab of Fluid Power Transmission and Control,Zhejiang University, Hangzhou 310027, China)

Abstract:The energy regulation device (ERD) is the key component of energy regulation based variable speed electro-hydraulic control system.And it determines the control effects. The structure of ERD is not complicated but it consists of three strongly nonlinear components: an accumulator, a proportional throttle valve and a relief valve, which increases the difficulty of analysis and design. The mathematical model of ERD is deduced firstly. The static characteristic analysis of the ERD is carried out. The transfer function of ERD is deduced by the mathematical model linearization. The effects of the accumulator volume, the precharge pressure and the proportional throttle valve on the ERD performance are analyzed in detail. The conclusion is deduced that the key problems of the ERD design are the capacity volume and the precharge pressure of the accumulator. The cylinder is taken as an example, the design principle of ERD is deduced, and some digital simulations under different volumes and precharge pressures of the accumulator are implemented. The experiments of valve control system, variable speed & valve control system and energy regulation based variable speed electro-hydraulic control system are also implemented. The results of simulations and experiments indicate that the design principle of the ERD is correct and feasible, thus laying the foundation for its practical applications.

Key words:Energy regulation device Accumulator Static and dynamical analysis Variable speed electro-hydraulic system

PP. 136-142

Mechanism of High-performance Liquid-liquid Displacement for Deep-sea Sensor Chamber

FAN Wei1,2PAN Huachen2CHEN Ying1,2

(1. The State Key Lab of Fluid Power Transmission and Control,Zhejiang University, Hangzhou 310027, China;2. Institute of Electromechanical Engineering, Hangzhou Dianzi University, Hangzhou 310032, China)

Abstract:A novel three-dimensional chamber of the deep-sea pH sensor is designed on the basis of gravity currents principle to facilitate online self-correction. The flows are driven by buoyancy differences between the interior and exterior fluids. A stable stratification and efficient displacement develop in this case. There are two water outlets in the chamber. Bottom gravity currents occur when the dense fluid enters through the inlet, displaces the light fluid in the chamber and pushes it out through high level outlet. On the other hand, surface gravity currents occur when the light fluid enters through the inlet, displaces the dense fluid in the chamber and pushes it out through low level outlet. Computationally, the distribution of velocity field and concentration field in the chambers is investigated with the computational fluid dynamics method. Experimentally the performances of the fluid displacement in the chambers are measured through the wine dye and the pH buffer solution displacement experiment and the effect of the Reynolds number and the Atwood number on the displacing efficiency is quantitatively investigated. Both computational and experimental results show that the barrel-shaped chamber of pH sensor (SS-Ι) cannot achieve full displacement, while the triangular prism chamber of pH sensor (SS-ΙΙ) can accomplish better liquid displacement as long as the sea water and buffer solution have different densities.

Key words:pH sensor Calibration Displacement Buffer solution

PP. 143-149

Bayesian Reliability Assessment and Prediction During Product Development

MING Zhimao1ZHANG Yunan1TAO Junyong1,2CHEN Xun1

(1. College of Mechatronics Engineering and Automation,National University of Defense Technology,Changsha 410073, China;2. Center for Risk and Reliability, University of Maryland,MD 20742, USA)

Abstract:A Bayesian reliability growth model of diverse populations based on the new Dirichlet prior distribution is studied. Aiming at some history and expert information during the development of a weapon, a Bayesian reliability growth model is presented based on the new Dirichlet distribution. Bayesian point assessment and confidence lower limit on product reliability at current stage are inputted by comprehensively making use of prior information and field test information at every stage.The method for determining prior distribution parameters is given by using the method, it is easy to confirm the parameters of prior distribution,it solves the problem of how to verify the hyper parameters of the new Dirichlet prior distribution in view of unclear physical meaning of these parameters. It solves the problem that the interference on parameters of Bayesian poster higher dimensions cannot be calculated indirectly. Then,the Gibbs sampling algorithm is used to compute the posterior inference.The Bayesian estimators and Bayesian lower bound are gained for the reliability of every stage. Furthermore, based on the test data, the model can be used to predict the product reliability, which extends the application range of the model. The analysis result of practical cases shows that the parameters of the Bayesian model have clear and definite meaning and are convenient to use for engineering applications.

Key words:Reliability growth model Bayesian analysis New Dirichlet distribution Markov chain Monte Carlo(MCMC) simula-ion Gibbs sampling

PP. 150-156

Non-probabilistic Model for Structural Reliability Based on Tolerance Analysis

HONG Dongpao MA Xiaobing ZHAO Yu SHEN Lijuan

(Department of System Engineering of Engineering Technology,Beihang University, Beijing 100191, China)

Abstract:Adequate data is necessary for probabilistic reliability model and fuzzy reliability model to analysis the new structure. To make up the gap by using the uncertain information of structures well, attempts are made to propose a new reliability model. The uncertain parameters of the structures are expressed as non-probabilistic interval variables. Then, the relation between tolerance and deviation of uncertain parameters of structures and its impact on the structural reliability are studied. Based on tolerance analysis, a non-probabilistic model for structural reliability is established. Furthermore, the character of the tolerance and the typical interference mode are analyzed according to the structural stress-strength interference model, and a new measure method of structural non-probabilistic reliability is proposed. A simple linear structure is taken as an example, the algorithm of non-probabilistic reliability is put forward and extended to the non-linear structures. Similarly, the algorithm for multiple linear structures is put forward and extended to the multiple non-linear structures. The presented model can be applied to any form of structural performance function, and is easy to use in engineering due to its convenient calculation, thereby providing quantitative basis for structural tolerance design and reliability analysis.

Key words:Reliability Structures Stress Strength Tolerance analysis

PP. 157-162

Preventive Maintenance Economic Optimization Model Based on Equipment Availability and Reliability

WANG Lingzhi XU Yugong ZHANG Jiadong

(School of Mechanical, Electronic and Control Engineering,Beijing Jiaotong University, Beijing 100044, China)

Abstract:Reliability centered preventive maintenance (PM) schedule plays an important role in production process, however it is always a complex task to make such a plan. Firstly single-component equipment optimal PM strategy is analyzed. Several PM activities are performed together to reduce shut down loss if they have reached the threshold for opportunity PM. On this basis, maintenance cost composition of multi-components systems and system availability are analyzed. The optimal group preventive maintenance model is proposed for complex systems. And the model minimizes maintenance cost and maximizes availability. A method of optimization of non-periodic PT for multi-components equipment with minimal repair at failures is discussed.Three types of PM actions including mechanical service, repair and replacement are simultaneously considered. Reliability-centered maintenance cost optimization model for multi-components system is built up. The optimal PM schedule which can provide desired levels of reliability to multi-components of the equipment and optimize maintenance cost and system availability at the same time is obtained by the simulation in Matlab program, which saves much cost and increases availability of the equipment compared with replacing or repairing components individually.

Key words:Preventive maintenance Reliability Optimization Availability

PP. 163-165

Modeling and Analyzing of Uncertain Time for Multi-process of Workflows with Resource Constraints

DU Yanhua1FAN Yushun2

(1. School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, China;2. Department of Automation, Tsinghua University,Beijing 100084, China)

Abstract:Because of imprecise measurement, incomplete information,fuzzy or fault description, etc, the temporal information of some workflows is usually indeterminate (or uncertain). According to the actual need for uncertain temporal modeling and analysis in workflow system,based on possibility theory, the concept of extended fuzzy timing workflow nets (EFTWFN) is proposed, which can describe all uncertain temporal information in a workflow. Under the condition of considering resource constraints, the method to analyze multi-process of EFTWFN models is presented. First of all, several inference rules between transitions of workflows are defined on the basis of EFTWFN and linear logic. Then, the total model is reduced and analyzed gradually according to the rules. The method can solve the qualitative and quantitative problems for concurrent workflows with resource constraints. Furthermore,it has higher efficiency and can complete the process of inference in the linear time complexity. In the end, an application of the method is illustrated through an example in manufacturing enterprise and its validity is indicated by simulation.

Key words:Resource constraint Multi-process Uncertainty Possibility theory Linear logic

PP. 166-176

Methodology for Determining the Final Importance Ratings of Engineering Characteristics in House of Quality Based on BSC

LI Yanlai1YAO Jianming2JIAO Minghai1

(1. Key Laboratory of Integrated Automation of Process Industry of Ministry of Education, Northeastern University,Shenyang 110004, China;2. School of Business, Renmin University of China,Beijing 100872, China)

Abstract:Determining the final importance ratings of engineering characteristics (ECs) is a crucial step of building house of quality (HOQ).For achieving the improvement goals of performances of ECs in an effective way, a balanced-card-based methodology for determining the final importance ratings of ECs is proposed. In this method, on the basis of the competitive evaluations of performances of ECs, a model for determining the competitive-evaluation-based importance ratings of ECs is built, and this model is resolved by using Lagrange function. Based on the integration of balanced scorecard (BSC), analytical hierarchy process and scale method, the importance rating of achieving the improvement target of performances (ITOP) of every EC is determined. Based on a combination of the initial importance rating, the competitive-evaluationbased importance rating, and the importance rating of achieving the ITOP of every EC, the final importance ratings of ECs are determined. A case study of product development of washing machine in a corporation is provided to illustrate the application of the proposed method.

Key words:House of quality Engineering characteristics Importance rating Balanced scorecard

PP. 177-185

Intelligent Process Quality Control System for Networked Manufacturing

JIANG Xingyu1,2WANG Shijie2ZHAO Kai1WANG Wanshan1

(1. School of Mechanical Engineering & Automation,Northeastern University, Shenyang 110004, China;2. School of Mechanical Engineering, Shenyang University of Technology, Shenyang 110178, China)

Abstract:Aiming at complicated and variable environment of networked manufacturing, how to settle the problems of monitoring dynamic and variable quality fluctuation, diagnosing the abnormal variation and adjusting the process at the right moment, is a difficult problem that faces the networked manufacturing enterprise in process quality control. An intelligent process quality control mode oriented to networked manufacturing, which integrates quality prevention, analysis, diagnosis and adjustment, and corresponding functional modules and framework, is put forward. This mode mainly deals with constructing and running dynamic quality control system, integrates theories and technologies such as the theory of similarity manufacturing, statistical process control (SPC),neural network. Furthermore, some of the key enabling technologies are studied in detail, including process quality analysis on-line based on similarity process, process quality diagnosis based on Elman and expert system of process quality adjustment. Finally, the prototype system of intelligent process quality control is developed by applying the development mode of JSP+Servlet and the network function interface of Java and Matlab, which is introduced as an example of some Heavy Machinery Ltd to demonstrate the rationality and validity of the method. It lays the foundation for realizing networking, intelligent and automatic process quality control.

Key words:Networked manufacturing Similarity manufacturing Elman network Expert system

PP. 186-194