第36卷第6期英文摘要



第36卷第6期英文摘要

Thermal Parameters Modeling Method and Sensor Fault Diagnosis Based on

KPCA-RBF Network

LiHongkun1,ChenJianhong1,2,ShengDeren1,2,LiWei1,2

(1.Institute of Thermal Science and Power System, Zhejiang University Hangzhou, 310027, China)(2.Key Laboratory of Refrigeration and Cryogenic Technology of Zhejiang Province Hangzhou, 310027, China)

Abstract In light of the problems of data monitoring and sensor fault diagnosis for thermal parameters in power plants, this paper builds an applied model based on mechanism analysis, kernel principal component analysis (KPCA), and radial basis function (RBF) neural network. First, auxiliary parameters related to the variable under study were obtained according to mechanism analysis. Then, KPCA was used to extract the high order nonlinear characteristics of the input variables, due to the high dimensionality, nonlinearity and strong coupling among them. Components were used to study and realize the reconstruction of thermal parameters through the RBF neural network. Last, sensor fault diagnosis was realized based on the prediction model and window moving method, and the fault data were able to be accurately replaced in time. Taking gas turbine outlet temperature as an example, the results show that this model performs with higher precision and generalization ability. Importantly, it can detect sensor faults and identify the type of fault in early stages, attaining a preferable detection effect.

Keywords mechanism analysis; kernel principle component analysis (KPCA); radial basis function (RBF) neural network; prediction modeling; sensor fault diagnosis

Seismic Analysis of Replaceable Steel Connection with Low Yield Point Metal

HeHaoxiang1,2,ChenKui1,LiRuifeng1

(1．Beijing Key Laboratory of Earthquake Engineering and Structural Retrofit, Beijing University of Technology Beijing, 100124, China)(2．Beijing Collaborative Innovation Center for Metropolitan Transportation Beijing, 100124, China)

Abstract The design for traditional steel rigid connections cannot fully meet the desired seismic requirements, though beam-column connections with weakened beam end can approximately realize the concept of “strong column-weak beam”, in which the local buckling in the weakened zone and the overall lateral may occur in strong earthquakes and have insufficient capacity. A replaceable steel connection with low yield point metal was proposed, based on the concept of earthquake-resilient structures. In this connection, the weakened parts in the flange slab and web plate were filled with low yield point metal, which yields then dissipates sufficient energy in earthquakes. Thus, damage to the main parts in the connection was slight, and the yield point metal could be replaced after the earthquake. The low yield point steel was selected as the replacement material, and the material constitutive relationship was obtained by a performance test. The seismic performance of the three types of connections, which include the traditional connection, beam end weaken connection, and replaceable connection under low cycle reciprocating load, were studied using the finite element method. In addition, the energy dissipation capacity and damage characteristics of different connections were compared. The multi-scale finite element models for the steel frames with different connections were analyzed by the inelastic time-history method. Both the computational efficiency and accuracy were assured. The analysis results approve that the replaceable connection can confine major damage in the replacement material and have better energy dissipation ability, safety reserves and resilience.

Keywords energy dissipation; low yield point metal; multi-scale model; replaceable connection;local buckling

Experiment and Calculation of the Low Frequency Performance of a Hydraulic Bushing with Multiple Tracks

YangChaofeng1,YinZhihong1,LüZhaoping2,DuanXiaocheng3,ShangguanWenbin1,3

(1.College of Automotive Engineering, South China University of Technology Guangzhou, 510640, China)(2.SAIC GM Wuling Automobile Co., Ltd. Liuzhou, 545007, China)(3.Ningbo Tuopu Group Co., Ltd. Ningbo, 315800, China)

Abstract The static and dynamic characteristics of hydraulic bushings with different numbers of inertia tracks and orifices were tested, and the working mechanisms of different hydraulic bushings were described. Furthermore, lumped parameter models of hydraulic bushings with multiple inertia tracks and orifices were proposed for estimating the dynamic stiffness and the loss angle. The relationships among the calculated dynamic stiffness and the loss angle with the number of the inertia tracks and the shape of the cross-section were analyzed and compared with the test data. A good correlation validates the proposed models, which can be used to analyze performances of hydraulic bushing with different structures before prototypes.

Keywords hydraulic bushings; multiple tracks; lumped parameter model; test analysis; parameter identification; dynamic performances

System Identification Based on HHT and Ideal Band-Pass Filter

WangQi′ang,WuZiyan,LiuLu

(School of Mechanics, Civil Engineering and Architecture, Northwestern Polytechnical University Xi′an, 710129, China)

Abstract Aiming at the mode mixing problem in the sifting process of empirical mode decomposition (EMD), a new approach for system identification (SI) based on Hilbert-Huang transform (HHT) and ideal band-pass filter was proposed. First, using Fourier transform, a rough estimation of the natural frequency was obtained from the frequency response function. Then, an ideal band-pass filter was designed, with passband determined through the half-power bandwidth method. The filter provides zero phase shift within the passband, and at the same time does not change amplitude spectra. The original response was filtered into a series of narrow band signals through designed filters. Further, narrow band signals were decomposed into modal responses using EMD. The Hilbert transform was applied to each modal response to construct the analytical signal. Finally, the least-square fitting was proposed to identify structural modal and physical parameters. Results show that the half power bandwidth method can realize the quantitative design of the passband. Zero phase shift characteristics of the ideal band-pass filter can better meet the requirements of HHT used in the SI. The combination of the two methods can effectively solve the mode mix problem, eliminate the false modal components and greatly improve SI accuracy.

Keywords system identification; Hilbert-Huang transform; ideal band-pass filter; empirical mode decomposition; half-power bandwidth method; modal response

Noise Reduction Features of Arbitrary Order Partial Differential Equations

YinAijun1,ZhangQuan1,2,DaiZongxian3

(1.State Key Laboratory of Mechanical Transmissions, Chongqing Unviersity Chongqing,400044, China)(2.Tianjin Electric Power Transmission & Transformation Engineering Corporation Tianjin, 300161, China)(3.No.1 Branch of Chongqing Academy of Metrology and Quality Inspection Chongqing, 402260, China)

Abstract According to the principle of fractional calculus, a unified model of arbitrary order partial differential equation (PDE) based noise reduction was proposed. The design method based on the numerical solution for arbitrary order PDE filter was realized. In particular, the filter features of arbitrary order PDE were analyzed. The numerical procedure has rapid implementation of the filtering procedure with one iteration, which has good time-consuming performance. De-noising tests were conducted on different degrees of artificial noise. Experimental tests have been rigorously compared with different de-noising methods to verify the efficacy of the proposed method. It turns out that the numerical process to PDE noise reduction has an excellent performance and a simple algorithm.

Keywords partial differential equations; arbitrary order; noise reduction; vibration signal

Characteristics of Micro-seismic Signal in the Static Cracking Process of Cement

ZhangSu1,2,WangJingui1,2,AiLihao2

(1.College of Environment and Resources, Fuzhou University Fuzhou, 350116, China)(2.Faculty of Resources and Safety Engineering, China University of Mining and Technology Beijing, 100083, China)

Abstract In order to study the characteristics of micro-seismic signals in the static cracking process of cement, the micro-seismic signals of the cement cylinder model in the static cracking processes were collected by a soundless cracking agent and ZDKT-1 type coal or rock dynamic disaster experimental simulation system. Hilbert-Huang transform (HHT) was used to analyze the microseism signals. The results show that: a. The process of static cracking could be divided into three stages: initial, middle and late. The amplitudes and energies of micro-seismic signals in the static cracking process did not change monotonically, but changed between weak and strong. b. The laws of micro-seismic signals in the static cracking process of different strength specimens were similar, but in high strength specimens, the micro-seismic signal arose later, lasted longer, and had higher amplitude and frequency. c. While the processes of static cracking were long, the microseism signals were paroxysmal and lasted under two seconds, with small amplitudes. The frequency distribution of the middle stage was wider than those of the initial and late stages, but their dominant frequencies were all lower than 50 Hz.

Keywords soundless cracking; micro-seismic signal; Hilbert-Huang transform; frequency

Analysis on Coupling Vibration Frequency Characteristics of Wind Turbine Blade Rotating Fatigue Loading System

LiaoGaohua1,2,WuJianzhong1,ZhangLeian1

(1.College of Mechanical Engineering,Tongji University Shanghai, 201804, China)(2.Jiangxi Province Key Laboratory of Precision Drive & Control, Nanchang Institute of Technology Nanchang, 330099, China)

Abstract In light of the characteristics of coupling vibration in the wind blade fatigue loading process, a dynamic blade fatigue loading system model block driven by a rotating eccentric was established. An electromechanical coupling mathematic model was derived using the Lagrange equation. The system dynamics equations were approximate analysis by using the averaging method, then the torque balance equation of vibration was obtained. Based on analysis of the variation in vibration frequency, the simulation model was established. Numerical simulations on the system frequency capture process, and revealed the characteristics of a self synchronous vibration system. Finally, the correctness of the mathematical model and simulation results was verified by the wind blade fatigue loading. The results showed that the blade frequency and vibration amplitude fluctuation when the deviation between the driving and natural frequencies of the blades was obviously large. The frequency deviation in a small range (0.47～0.62 Hz), eccentric rotary system and blade will appear in frequency capture, and then amplitude tended to be stable, but decreased. When the load torque was larger and the motor power was insufficient, the eccentric block will rotate speed jump.

Keywords fatigue test; wind turbine blade; coupling; frequency characteristics; simulation

Stochastic Subspace Identification Considering Large Amplitude Inputs

QinShiqiang,KangJuntao,ZhouWangbao

(School of Civil Engineering and Architecture, Wuhan University of Technology Wuhan, 430070, China)

Abstract Stochastic subspace identification (SSI) is a robust time domain modal identification algorithm. Generally, SSI identifies modal parameters from dynamic responses of structures under zero initial condition, while the effects of large amplitude inputs on the results are neglected. Based on existing studies, this paper presents the effects of large amplitude inputs on SSI and investigates the applicability of this method. First, the theoretical foundation of SSI considering large amplitude inputs is briefly introduced. Then, through a two degrees of freedom system, the relative accuracy of different modes and mode shapes changes with data of samples, and the large amplitude inputs are studied. Finally, a case study of the fluctuation test of the arch rib of the Yangtze River Caiyuanba Bridge is presented to investigate the applicability of the method in identifying large amplitude inputs. The study shows that considering large amplitude inputs can improve the relative accuracy of modal parameters. Compared to natural frequency, the accuracy of mode shape change with data samples shows more randomness. SSI of large amplitude inputs has a high standard for the completeness of modal experiment.

Keywords bridge engineering; modal parameter; large amplitude inputs; stochastic subspace identification; Monte Carlo

A Method of Enhancing the Fault Characteristics in Early Stage of Rolling Bearing Based on Phase-Space Reconstruction and ICA with Reference

BoLin1,LuChao1,ZhaoXin2

(1.State Key Laboratory of Mechanical Transmission, Chongqing University Chongqing, 400044, China)(2.Wuhan Raycus Fiber Laser Technology Co., Ltd. Wuhan, 430000, China)

Abstract In the early stages of rolling bearing fault diagnosis, the characteristic frequencies of different parts are weak and difficult to identify. Thus, this paper presents a method to enhance the interested frequency components of rolling bearing. This method has better results and higher resistance to interference frequencies than do traditional methods using phase-space reconstruction to expand the time-domain signal into a high dimension space and independent component analysis with reference (ICA-R) to find the closest component to the reference signal. The simulation results and actual measurements of signals prove that this method is effective and feasible in early stage fault diagnosis, and also has certain values for engineering applications.

Keywords characteristics enhancement; rolling bearing; early stage diagnosis; phase-space reconstruction; independent component analysis with reference (ICA-R)

Vibration Analysis of Tracked Vehicle Considering Wheel′s Diameter

SunZhongxing,TangLiwei,WangWei,DaiYingjie

(Department of Artillery Engineering, Ordnance Engineering College Shijiazhuang, 050003, China)

Abstract Generally, the vibration analysis of vehicles takes road roughness as displacement excitation, ignoring the effect of the geometric relationship between wheel and road. This paper analyzes the influence of the crawler-vehicle bogie wheel′s diameter on the displacement excitation and deduces the equations for the calculation of the displacement excitation, considering the influence of the track filtering effect and wheel′s diameter. Then, the vertical vibration state equations and corresponding simulation model were formulated, and the vibration of a vehicle moving on the wavy and practical road were analyzed. The results showed that the analysis that considered the crawler-vehicle bogie wheel′s diameter better simulated the practical conditions with more information. Finally, experiments verified the ability of the proposed method to calculate displacement excitation.

Keywords tracked vehicle; pavement roughness; wheel′s diameter; displacement excitation; equation of state

Analyses of Flow Influence in Low Frequency Sonophoresis

PengHanmin,YuBoping,MaoTing,ZhuPancheng,ChenZhijun

(State Key Lab of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics Nanjing 210016, China)

Abstract In order to analyse the mechanism of acoustic and flow coupled fields in the low frequency sonophoresis (LFS) process, an acoustic-piezoelectric-fluid model was built based on the piezoelectric equation, acoustic equation, and turbulence k-ε model, by using the finite element software COMSOL. The amplitudes and distributions of acoustic and flow fields in LFS were calculated, and the drug permeation of an in vitro transdermal experiment was measured after 90 minutes of ultrasonic radiation. The simulated and experimental results showed that there was a large amount of cavitation and folding on the skin of LFS, which suggested that the acoustic cavitation effect and alternating load occur on the epidermis, and that the folds may have been caused by water flow or vortex flow field. Further, the flow began on the sound radiation surface in an ultrasonic transducer and circulated to the transducer′s horn profile, contributing to the stirring effect; the largest value of flow velocity happened under the radiation face and reached 0.55 m/s when the input electrical power was 5.5 W, accompanied with eddy currents above the skin; and acoustic field helps promote permeability in LFS, and the flow field can mix drug solution and expand permeation channels role to support the promotion.

Keywords low-frequency sonophoresis; transdermal drug delivery; ultrasonic transducer; flow;finite element method (FEM)

The Vibration Test of Power Transformer Scale Model and Its Acoustic Model

HuangGuoxing1,RuanXueyun1, 2,LiZhiyuan1,WeiHaozheng1

(1.Institute of Sound & Vibration Research, Hefei University of Technology Hefei, 230009, China)(2.School of Mechanical Engineering, Anhui University of Science and Technology Huainan, 232001, China)

Abstract A power transformer is one of the main sources of noise in the power transmission and transformation system, and the accuracy of outdoor noise prediction directly affects noise evaluation and control. Based on the test results of the wall vibration phase and amplitude in different excitation frequencies, this paper concluded that the distribution of the model phase and amplitude were random when the excitation frequency reached up to the seventh modal frequency. Thus, the zoned format could be simplified from power transformer to point sound source. Further, the coherent image source model of the power transformer was established considering the interference effect among the infinite image sources caused by the multiple reflections of sound rays. Finally, the sound field of the power transformer groups was calculated using the proposed model, and the solution was compared with that using the ISO9613 and BEM model. The results show that the coherent source model can predict the trend of the spread of sound waves at different locations considering the phase information, and the calculated value was closer to the exact value than that of the ISO9613 model. The above research results validate the proposed theoretical model.

Keywords power transformer; vibration test; reduced scale model; noise prediction; coherent image source method; half-open space

Design and Experiment of a Microflow Stabilizer for Eliminating the Pulse of Piezoelectric Micropump

WuXuan1,2,ChenLiguo1,2,HeWenyuan1,2,PanMingqiang1,2

(1.Robotics and Microsystems Center, Soochow University Suzhou, 215021, China)(2.Collaborative Innovation Center of Suzhou Nano Science and Technology Suzhou, 215021, China)

Abstract This paper presents a microflow stabilizer, which contains a fluid capacitor and a microchannel that can reduce the fluctuation of the pulsatile flow generated by a piezoelectric micropump. A parameter model was developed and the dynamic simulation was presented in order to study the dynamic device characteristics. Simulation showed that larger fluidic resistance of the microchannel, higher pump frequency, and larger capacitor radius contributed to better flow stabilization. Experiments were conducted to verify the effectiveness of the stabilizer, and the results showed that the designed microflow stabilizer could ensure stable flow in a piezoelectric pump.

Keywords stabilizer; fluidion pulsation; microflow; piezoelectric micropump

Research on Characteristics of Transmission Rattle Based on Rigid-Flexible Coupling Model

DingKang1,2,ChenZhiqiang1,2,YangZhijian1,2

(1.School of Mechanical Automotive Engineering, South China University of Technology Guangzhou, 510641, China)(2.Ministry of Education′s Key Laboratory of Advanced Automotive Components Manufacturing Technology,Chongqing University of Technology Chongqing, 400054, China)

Abstract In order to research the characteristics of the transmission gear rattle, a special test transmission containing only two stalls was designed. The test transmission considered the complex relationship between each part, internal dynamic excitation of gears, engine speed fluctuation and load incentives, bearing stiffness and damping characteristics, and flexible properties box. A transmission rigid-flexible coupling multi-body dynamics model was built in LMS virtual lab software. The condition of transmission gear system rattle was introduced, and an accurate expression of rattle time history and each factor was derived. Finally, each rattle factor was analyzed systematically based on the rigid-flexible coupling model. The results showed that the rattle can be controlled in the ideal range through rational design of the gear system parameters.

Keywords transmission; rattle; rigid-flexible coupling model; rattle time history

Investigation on Milling Stability Lobe Construction Based on Milling Force Simulation

LiHongkun1,2,ZhouShuai1,2,RenYuanjie1,2,CongMing1,2,ZhaoPengshi1,2

(1.School of Mechanical Engineering, Dalian University of Technology Dalian, 116024, China)(2.Dalian Xinyu Science Technology Development Center Co., Ltd. Dalian, 116024, China)

Abstract Optimizing the parameters of the milling process is important for improving processing efficiency, and is based on milling stability lobe construction. However, since the milling force of real work-pieces is not measurable during production, milling force simulation is introduced to analyzed the milling stability lobe graph. First, the milling force and milling coefficients were obtained using finite element simulation. Then, experiments were carried out to obtain the modal parameters of a tool-machine system. Finally, milling stability lobes were constructed based on the above analysis, and the effectiveness of the lobe was verified with an actual manufacturing process. This research can provide a reference for the inhibition of chatter in the milling process by improving the machining efficiency and enhancing the system′s stability. Moreover, it can benefit the actual selection of machining parameters for milling processes.

Keywords milling force; milling stability; simulation; parameter optimization

Control Strategy for Electro-hydraulic Servo Test Bench for Shock Absorber

WangCuntang,ZhangKai,ZhangBing,XieFangwei,XuanRui

(School of Mechanical Engineering, Jiangsu University Zhenjiang, 212013, China)

Abstract In order to meet the urgent requirements of manufacturing, testing and development in the domestic automobile shock absorber industry, a new kind of shock absorber test bench was established to test the response performance of shock absorbers in complex load spectrums, and to study the servo control strategy. Three state control strategies were used to improve the system response and tracking accuracy. Meanwhile, system models were built and simulated based on Matlab/Simulink software. Comparison between the simulation and experimental results proved that these three state control strategies can guarantee the stability of the system, improve the system bandwidth, and ensure the accurate measurement of the shock absorber damping force and acceleration attenuation on the test bench.

Keywords shock absorber; test bench for hydraulic; control strategy; Matlab/Simulink

Modal Analysis of Structures Based on Hankel Matrix Joint Approximate Diagonalization Method

ChengLin1,2,YangJie1,ZhengDongjian2,RenJie1

(1.State Key Laboratory Base of Eco-Hydraulic Engineering in Arid Area, Xi′an University of Technology Xi′an,710048, China)(2.State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University Nanjing, 210098, China)

Abstract To overcome some limitations of the modal identification method based on the second-order blind identification (SOBI) algorithm, a new modal parameter identification method based on the Hankel matrix joint approximate diagonalization (HJAD) technique was proposed. In this method, the Hankel matrix, which is commonly used by the stochastic subspace identification method, was diagonalized using the joint approximate diagonalization technique in order to separate modal responses and identify modal parameters. Compared with the SOBI-based modal parameter identification method, the proposed method was easy to implement when only additional time-lagged response data was needed. The numerical and experimental analysis results show that the proposed modal parameter identification method overcame the limitation of not being able to estimate more active modes than the number of available sensors.

Keywords operation modal analysis; blind source separation; second order blind identification; Hankel matrix joint approximate diagonalization; shaking table test

The Influence of Rotor Crack on Dynamic Changes Rule of Turbine Tip Clearance

JiaBinghui1, 2,FengYong1,YanGuodong1,ZhangJie1

(1.School of Mechanical Engineering, Nanjing Institute of Technology Nanjing, 211167, China)(2.Key Laboratory of Road Construction Technology and Equipment, Chang′an University Xi′an, 710064, China)

Abstract In order to guide tip clearance dynamic measurement and active control, a model of the turbine rotor of an air engine was built, and the effects of cracks of different depths and locations in the blade or disk were investigated, considering the thermal stress and centrifugal force of the rotor. The results show that the variation range of tip clearance increases with crack depth: the range increased by 0.11, 0.38 and 0.9 mm compared to the normal condition when the distance of crack to blade tip was 0.005, 0.025 and 0.04 m, respectively, with the ratio of the crack′s depth to width maintained at 0.5. Meanwhile, when the crack occurred at the blade root, the tip clearance variation range significantly increased compared with the effect of uniform stress, and the tip locus was greatly dissymmetric during the period of engine acceleration and deceleration.

Keywords blade tip clearance; aero-engine; crack rotor; dynamic model

Feature Extracting Method in the Rolling Element Bearing Fault Diagnosis Based on EMD and Spectrum Auto-correlation

WanShuting1,ZhanChanggeng2,DouLongjiang1

(1.Department of Mechanical Engineering, North China Electric Power University Baoding,071003, China)(2.Industrial Turbine Academy Turbomechanical Institute, Hangzhou Steam Turbine Co., Ltd. Hangzhou,310022, China)

Abstract This paper pointed out and verified the limitations of the spectrum auto-correlation (SAC) method based on the analysis process of empirical mode decomposition (EMD) and mechanism of bearing fault. Then, a feature extracting method of bearing fault diagnosis combined with EMD and SAC (EMD-SAC) was proposed, which analyzed the intrinsic mode function (IMF) based on EMD and chose the appropriate component to analyze using SAC. With this method, the bearing failure frequency could be separated from the complex signal. Finally, the inner and outer ring fault of deep groove ball bearings and cylindrical roller bearings respectively were tested in laboratory. The fault vibration data was measured and analyzed to verify the theoretical analysis presented above.

Keywords empirical mode decomposition (EMD); spectrum auto-correlation (SAC); bearing fault; kurtosis; feature extracting

Bearing Weak Fault Signal Detection Based on Adaptive Multi-stable Stochastic Resonance

FengYi,LuBaochun,ZhangDengfeng

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

Abstract In light of the low efficiency of the bistable stochastic resonance model in modulated signal processing, an extraction and detection method for weak signals was proposed based on adaptive multi-stable cascaded stochastic resonance (AMCSR). First, the vibration signal was demodulated, and the multi-stable stochastic resonance model was adopted, according to the distribution feature of the upper and lower envelope signal. Second, the stochastic resonance model parameters were optimized adaptively through the ant colony algorithm, which adopted the fault feature frequency amplitude as the optimization index. Finally, the fault feature frequency of the envelope signal was progressively strengthened through the optimal cascaded stochastic resonance system with noise as the energy source, then the enhanced output signal was obtained. Experimental results of the bearing vibration signal analysis show that, through the AMCSR method, the fault feature frequency components can be strengthened, and the weak fault signal can be effectively extracted from the mixed signal.

Keywords rolling bearing; envelope signal; multi-stable; stochastic resonance

Fundamental Dynamic Characteristics of Double Tuned Liquid Column Damper for Suppressing Harmonically Forced Oscillations

YanWeiming,NiMing,WangJin

(Beijing Laboratory of Earthquake Engineering and Structural Retrofit, Beijing University of Technology Beijing, 100124, China)

Abstract Taking the advantages of tuned mass damper (TMD) and tuned liquid column dampers (TLCD) in civil engineering vibration control, a double tuned liquid column damper (DTLCD) was presented considering the cost and efficiency of vibration attenuation used in civil engineering. The motion equation of the DTLCD-single-degree-of-freedom (DTLCD-SDOF) system under harmonic excitation was established, of which the dynamic magnification factor (DMF) was derived. Then, an optimization strategy and evaluation function was proposed to judge the parameters of DTLCD, and a parameter optimization program written in Matlab was used to optimize DTLCD. Effects of each parameter on dynamic magnification factor (DMF) were discussed, as well as the robustness of DTLCD when the damping ratio and frequency were changed. Finally, the effectiveness and robustness of DTLCD was compared with that of the TMD, TLCD and DTMD. The theoretical and numerical results showed that the effectiveness of DTLCD was much better than of the TMD and TLCD, and was the same as that of DTMD; meanwhile, DTLCD had the best robustness in terms of perturbation of structure frequency. It was concluded that DTLCD is a very effective method of vibration control.

Keywords double tuned liquid column damper (DTLCD); double tuned mass damper(DTMD); optimization design; harmonically forced oscillations; effectiveness; robustness; vibration control

Dynamic Characteristic Analysis of Arch Dams with Different Forms of Reservoir Water Coupling

ZhangJianwei,CaoKelei,ZhaoYu,JiangQi,LiuXiaoliang,BaoZhenlei

(College of Water Conservancy, North China University of Water Conservancy and Electric Power Zhengzhou, 450011, China)

Abstract In order to study the influence of different reservoir water models on arch dam structural dynamic characteristics, an added masses model and fluid solid interaction(FSI) system model of a Laxiwa arch dam were set up. The results of finite element simulation were compared with the identification results of stochastic subspace identification (SSI) based on wavelet threshold combined with the empirical mode decomposition (EMD) filtering method. The comparison shows that the structural dynamic characteristics were reflected by both coupled models, and the frequency error margin for the added masses model calculation results to the identification results was 0.41%～7.55%, while that of the FSI system coupled model was 0.09%～3.19%. The FSI system model was superior to the added massed model with a smaller error at each frequency order. Additionally, the frequency space of contiguous order of the FSI system model was relatively stable. This study shows that the FSI system coupled model can reflect the arch dam vibration information comprehensively and accurately in terms of simulation order number and precision. The FSI system coupled model can be applied in the dynamic characteristics analysis of arch dam structure, and used as a reference of the finite element model in the research of diagnosing arch structural damage.

Keywords arch dam; added masses model; fluid solid interaction (FSI) system model; wavelet threshold-EMD filtering method; modal identification with stochastic subspace identification (SSI) method

Research on the Dynamic Behavior of O Type Wire-Cable Vibration Isolator in Three Modes

WangHongxia1,2,GongXiansheng1,PanFei1,GeJianbing1

(1.The State Key Laboratory of Mechanical Transmission, Chongqing University Chongqing, 400044, China)(2.College of Mechanical Engineering, Hubei University of Automotive Technology Shiyan, 442002, China)

Abstract A series of dynamic tests was carried out on an O type wire-cable vibration isolator by imposing cyclic sinusoidal motion to obtain its variations in hysteretic behavior with excitation amplitude and frequency in shear, roll and tension-compression, respectively. In shear and roll modes, the isolator exhibited symmetric hysteresis loops under cyclic loading. In the tension-compression mode, the isolator exhibited asymmetric hysteresis loops. As the displacement amplitude increased, stiffening and softening occurred along the tension and compression direction, respectively. The hysteresis loop area increased, and the asymmetric hysteresis became apparent. The rate-independent nature of wire cable isolators in the tested frequency range has been experimentally verified in shear, roll and tension-compression. A modified normalized Bouc-Wen model and a simple yet effective identification method were proposed to describe the hysteretic behavior of the isolator in three modes. The proposed model and identification method were validated with the results, which verified that the predicted hysteresis loops were close to the measured hysteresis loops, and the proposed model and method were effective for describing dynamic hysteresis behavior of vibration isolator in three modes.

Keywords O type wire-cable vibration isolator; hysteresis behavior; parameter identification; normalized Bouc-Wen model

Multi-objective Optimal Sensor Placement Method and Its Application

LiShilong1,2,MaLiyuan1,LiYongjun1,WangTianhui1

(1.Department of Missile Engineering, Ordnance Engineering College Shijiazhuang, 050003, China)(2.Taiyuan Satellite Launch Center Taiyuan, 030027, China)

Abstract In order to solve the problem of optimum sensor placement in the damage detection of complex structures, this paper presents a multi-objective optimum sensor placement method (MO-OSP). An integrated information matrix was deduced from the structural motion equation, which includes information on mode independence, damage sensitivity and modal strain energy. Based on the information entropy, an objective function was set up with the criterion of maximum norm of the information matrix and minimum condition number of the sensitivity matrix, and then the sensors optimization was carried out. The improved MO-OSP method was compared with three typical optimal sensor placement methods in terms of several evaluation criteria based on damage tests on the launch platform. Numerical example analyses showed that the improved method could not only ensure the linear independence of mode shapes and damage sensitivity, but also had outstanding robustness, thus making it an ideal method for solving the problem of optimum sensor placement in the damage detection of complex structures.

Keywords multi-objective; optimal sensor placement; damage detection; modal parameter; launch platform

Impact and Locating Method Research on Satellite′s Typical Composite Honeycomb Structure Panel

ZhaoFagang1,ZhouChunhua1,LiangDakai2,LiuZhao3,ShiRui2

(1.Laboratory of Space Mechanical and Thermal Integrative Technology,Shanghai Institute of Satellite Engineering Shanghai, 200240, China)(2.State Key Laboratory of Mechanics and Control of Mechanical Structures,Nanjing University of Aeronautics and Astranautics Nanjing, 210016, China)(3.Shanghai Institute of Spaceflight Control Technology Shanghai, 201109, China)

Abstract A satellite can be damaged because its main component, a composite material honeycomb panel, is easily impacted by space debris and explosive devices. Monitoring the impact location is an important step to ensure the safe and reliable operation of satellites in orbit. A sensing system based on fiber Bragg grating(FBG) was built in order to monitor the impact signals of a typical composite honeycomb sandwich structure in real time. The wavelet packet energy spectrums of these impact response signals were analyzed, and the energy of 16th decomposition level was observed to be sensitive to impact and could thus be regarded as the feature values. Impact locations were predicted by means of the energy and amplitude ratio. The results showed that the average error for the test was 1.87cm. Thus, this method can effectively determine the impact position, which provides a strong basis for satellite structure health monitoring.

Keywords composite materials honeycomb panel; fiber Bragg grating; impact localization; wavelet packet analysis

Adaptive Neighborhood Selection Manifold Learning Algorithm and Its Application in Fault Diagnosis with Dimensionality Reduction

ZhangXiaotao,TangLiwei,WangPing,DengShijie

(Department of Artillery Engineering, Ordnance Engineering College Shijiazhuang, 050003, China)

Abstract In light of neighborhood selection of a manifold learning algorithm, a novel adaptive neighborhood selection method was proposed. The adjacency matrix was calculated by Mahalanobis distance, then used to obtain the initial neighborhood. The final neighborhood was obtained through regulation of the initial neighborhood using Gauss kernel density estimation of all samples. The improved principal component analysis locality preserving projection (PCA-LPP) manifold learning algorithm using adaptive neighborhood selection was applied in the processing of gearbox fault signals. The results showed that the eigenvectors obtained by adaptive neighborhood selection had a more satisfying fault identification rate than that obtained by k neighborhood and original eigenvectors, reaching as high as 94.67%.

Keywords adaptive; neighborhood; Gauss kernel density estimation; manifold learning; fault diagnosis

The Study of Turbine Blade Vibration Based on the Finite Element Method

WangNanfei1,NanGuofang2,JiangDongxiang1

(1.Department of Thermal Engineering, Tsinghua University Beijing, 100084, China)(2.School of Energy and Power Engineering, University of Shanghai for Science and Technology Shanghai, 200093, China)

Abstract Based on the vibration theory of the turbine blade, the first seven orders of tangential bending natural frequency of vibration for the blade were calculated in the laboratory using the theory method and finite element method, then compared. The simulation analysis of the vibration mode of the blade and interlocked joint for the turbine shrouded blade group were carried out under different rotational speeds using the finite element method. The analysis results were obtained and compared, considering the dynamic stiffening effect. For the blade group, at the top of which the shrouds were not connected, the shroud contact issue was solved by constructing a spring modal and using the finite element method. The results were a true reflection of shroud collision and blade vibration during operation of the turbine.

Keywords turbine blade; modal analysis; finite element method; dynamic stiffening; spring modal; contact

Torsional Vibration Model Updating for the Mill Transmission System Based on Response Surface Method

TaoZheng1,LiuXu1,GuoQintao2

(1.School of Mechanical Engineering, Zhengzhou University Zhengzhou, 450001, China)(2.College of Mechanical Electrical Engineering, Nanjing University of Aeronautics and Astronautics Nanjing, 210016, China)

Abstract The torsional vibration of a large equipment transmission system affects its normal operation and even leads to serious damage. An effective means to relieve the torsional vibration is avoiding resonance. A large mill equipment was targeted, and its transmission system was analyzed based on the revising theory of the finite element model (FEM) of the response surface. A response surface model was built to approach the complicated implicit function of the characteristic quantity and design parameters. After choosing the significant parameters, the probable errors existing in the FEM model of the system were revised. Then, the transmission system was optimized based on the new FEM, and its modal frequency was adjusted to avoid the working frequency by updating the FEM. Finally, the optimization of the transmission system was achieved, which indicates that this method can guide the design of the transmission system.

Keywords transmission system; response surface method; model updating; torsional vibration

Research on the Non-filter Air Cleaning Device Based on Ultrasonic Atomizer

WangJinpeng1,QiZhaoyang1,ZhuZesen1,LiuJie1,ShiYunlai2

(1.School of Mechanical and Electronic Engineering, Nanjing Forestry University Nanjing, 210037, China)(2.State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics Nanjing, 210016, China)

Abstract China′s rapid expansion has tremendously increased the number of heavy haze days in the megacities and their vicinities. Indoor air quality and public health have also become significant research topics. This paper summarizes theories on cloud droplets capturing fine particulate matter, and describes the production of a non-filter air cleaning device based on ultrasonic atomization technology and negative ion technology. Then, several experiments were carried out in an 8 m3simulation cabin. Experimental results showed that the air cleaning device could decrease the PM2.5concentration in the simulation cabin by 44.2% within 20 minutes, and down from 382.7μg/m3to 72.3μg/m3in about 50 minutes. This confirmed that the cleaning ability and efficiency of the air purification device was good, and the air purifying program was feasible. At the same time, there was no secondary pollution to the indoor air environment caused by a dirty filter that had not been replaced in time. Moreover, the air cleaning device has the function of regulating indoor humidity.

Keywords haze; indoor environment; air purification; ultrasonic atomizer; negative ions

(End of the Volume 36)

Current Status and Trends of Tactile Sensing and Display

ShuaiLiguo,ChenHuiling,HuaiHongqi

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

This paper describes the current technologies of tactile perception, sensing and display around the world. On the basis of comprehensive analysis, this paper points out that the development of tactile sensing and display technology have been moving away from tele-presence applications and may become two independent research directions. Tactile sensing mainly focuses on the fields of intelligent robots and medical rehabilitation, while tactile display might cover more fields, including virtual reality, film and television, games and entertainment, industrial design, drawing and painting, education and training, and industrial touch screens, besides the traditional applications of robot tele-presence and tactile vision substitution. This paper concludes by presenting the future trends of tactile fields.

tactile perceiving; tactile sensing; tactile display; virtual reality