第39 卷第1 期英文摘要

Modeling and Response Analysis of a Multi-field Coupled Multi-direction Vibration Energy Harvester

ZHANG Xuhui， WU Zhonghua， LAI Zhengpeng， TAN Houzhi， FAN Hongwei

( School of Mechanical Engineering，Xi'an University of Science and Technology Xi'an，710054，China)

AbstractAiming at low response performance of vibration energy harvester to low-frequency and low-amplitude excitation，the nonlinear magnetic attraction is added to energy harvesting structure to improve frequency band and energy conversion efficiency． Nonlinear magnetic models are studied，the distributed electromechanical coupled models of transverse and longitudinal vibrations are established by using the generalized Hamilton variation principle， and system dynamic equation is addressed dimensionless and solved numerically． The experimental platform of vibration energy harvester is built，the spectral characteristics and response output is obtained． Results show that， when magnet spacing is 15 mm and excitation amplitude is 0．5 m/s2，the energy conversion efficiency increases by about 6 times compared with that with no magnetic，and resonance frequency decreases from 18 Hz to 9．5 Hz， which solves problems of narrow band，high response frequency and the low output voltage of piezoelectric energy harvester．

Keywordslow-frequency and low-amplitude vibration; multi-field coupled model; vibration energy harvester; distributed model; response analysis

Micro-crack Detection of Nonlinear Lamb Wave Based on Lyapunov Exponent

BO Lin， TANG Tao， LIU Xiaofeng， WEI Daiping

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

AbstractIn order to improve the detection accuracy of nonlinear Lamb for structural micro-cracks under background noise interference，the Duffing system and Lyapunov exponent are used to enhance and quantify the nonlinear Lamb characteristics under noise interference． Firstly，the Poincare diagram is used to determine the dynamic parameters of the Duffing system，and then the Lamb waves nonlinearly extended are input into the adjusted Duffing system． Lastly，the method uses the phase space reconstruction of the system output time series to obtain the corresponding Lyapunov exponent． Simulation results of several model data show that there is a good linear relationship between the Lyapunov exponent and the crack size even in the case of noise． This method has an obvious advantage for the identification of microcracks defects under noise interference，which is very important to improve the detection sensitivity of nonlinear Lamb wave．

KeywordsKeywords nonlinear Lamb wave; Duffing oscillator; Lyapunov exponent; micro-cracks

Composition Analysis of Damping Loss of Steel /Composite Materials Composite Structure for Ships

TANG Yuhang1， MEI Zhiyuan2， CHEN Zhijian2

( 1． Unit 92578 of the People's Liberation Army of China ( PLA) Beijing，100161，China) ( 2． Department of Naval Architecture Engineering，Naval University of Engineering Wuhan，430033，China)

AbstractThe use of superior damping composite materials for submarine vibration and noise reduction design has been relatively common，as a typical construction unit form，the damping properties of a steel /composite plate-shell composite structure are closely related to the response of the structure in the resonant region． Based on the viscoelastic damping theory，the damping dissipation mechanism is described，and the composition of the loss factor in the system is discussed based on the statistical energy theory． It is pointed out that the structural loss of a variety of composite materials is related to the material composition and mode，and the sound radiation loss is obviously affected by the fluid medium and shell nature． The internal loss factor tests of the steel plate and the glass fiber reinforced resin shell plate are completed in four working conditions． Combining with numerical calculations，the loss law of the experimental model is summarized，and its boundary loss factor is predicted． The results show: the sound radiation loss in the air is only about 1 /40 of the water's in the same model composition and boundary conditions; the boundary loss contributes greatly to the internal loss factor of the system in the condition of screws，laps and other non-rigid form of connection，particularly for the steel plate model． The overall damping performance between this kind of connection form and free boundary state exists a difference of several times．

Keywordsinternal loss factor; boundary loss; steel structure; composite shell plate; fluid; damping

Damage Identification Based on Modal Strain Energy Formulated by Strain Modes

ZHOU Jixiang1， WU Shaoqing1，2， DONG Eliang1，2， FEI Qingguo1，2

( 1． Department of Engineering Mechanics，Southeast University Nanjing，210096，China) ( 2． Jiangsu Key Laboratory of Engineering Mechanics，Southeast University Nanjing，210096，China)

AbstractThe traditional modal strain energy calculation needs complete modal shape information． However，it is difficult to accurately obtain the freedom of rotation from the mode shape information． In order to solve the problem， modal strain energy damage identification based on strain mode is studied，and the quantitative identification of structural damage is presented． Based on the relationship between strain and displacement，the transformation matrix between displacement mode and strain mode is obtained; the damage identification equations are derived based on the sensitivity analysis，through the substitution of the displacement modes with strain modes． The structural damage is finally identified via solving the equations using a singular value truncation method． Taking a beam structure with two fixed end as an object，the numerical simulation and experimental investigation are conducted． The results show that both the damage location and severity can be effectively identified from the new proposed method in this paper． Compared with the damage identification method based on modal strain energy and modal expansion， this proposed method has better accuracy and performance under noisy data． The research achievement has a potential value on the structural damage identification of engineering structures．

Keywordsstructural damage identification; modal strain energy; strain mode; sensitivity analysis; singular value truncation

Vibration Feature Extraction Based on Generalized Fractal Dimension and Kernel Principal Component Analysis

WEI Xiang1， LI Benwei1， WU Yiming2

( 1． Aeronautical Fundamentals College，Naval Aviation University Yantai，264001，China) ( 2． Luoyang Bearing Research Institute Co．，Ltd Luoyang，471039，China)

AbstractFor the problem of rotary machine nonlinear feature extraction，a method based on generalized fractal dimension ( GFD) and kernel principal component analysis ( KPCA) is proposed． Firstly，GFD is used for feature extraction and formed a high dimensions feature space． Secondly，KPCA is used for dimensionality reduction in high dimensions space and feature extraction ulteriorly． Finally，data in different running conditions of a rotor system and faulty bearing are classified using the methods of KPCA and K nearest neighbor ( KNN) ． The result shows that this GFD-KPCA method can effectively extract features，accurately classify data in different conditions，and has a low dependence on selecting parameters． Bearing weak fault vibration feature extraction results show that the performance of GFD-KPCA is better than that of conventional KPCA feature extraction algorithm，which has better accuracy and scope of application．

Keywordsrotary machine; generalized fractal dimension; kernel principal component analysis; feature extraction; fault classification

A Measurement Method for the Sensitivity of a 3D Particle Velocity Sensor

JING Wenqian1，2， WU Huawei1，2， NIE Jinquan1，2， DING Huafeng1，2

( 1． Hubei Key Laboratory of Power System Design and Test for Electrical Vehicle，Hubei University of Arts and Science Xiangyang，441053，China) ( 2． School of Automotive and Traffic Engineering，Hubei University of Arts and Science Xiangyang，441053，China)

AbstractCurrently，the solution for obtaining the sensitivity of the particle velocity sensor is usually up to some special facilities or sound sources in order to create an environment where the acoustic impedance is known，and the sensitivities at three directions need to be obtained one by one． A method based on the nearfiled acoustic holography can compute the acoustic impedance through measuring or reconstructing the sound pressure and particle velocity without any special facility or sound source，and then obtain the sensitivity of the particle velocity sensor． This method is going to be extended to measure the sensitivity of a 3D particle velocity sensor． When the normal particle velocity is measured or reconstructed，the tangential particle velocity is also measured or reconstructed，and thus the 3D acoustic impedance can be estimated at the same time and the sensitivities of a 3D particle velocity sensor at x，y and z directions are able to be obtained simultaneously． Finally，an experiment is carried out to verify the efficiency of the proposed method．

Keywords3D particle velocity sensor; sensitivity; nearfiled acoustic holography; acoustic impedance

Design of Piezoelectric Driving Needle-Free Syringe Pulse Power Supply

LIANG Li， DONG Yikui， ZHANG Tiemin

( College of Engineering，South China Agricultural University Guangzhou，510642，China)

AbstractIn this paper，a pulsed power supply with needle-free syringe is designed． The drive control system of the pulse power supply is 12 V DC voltage supplied by the battery． Moreover，the Buck and push-pull circuit cascade circuit Boost rectifier filter outputs 0～400 V DC adjustable voltage，and the feedback circuit is used to correct the output voltage． Finally a full-bridge inverter circuit is applied to achieve adjustable output frequency and duty cycle． In this case，the output voltage can linearly change in 0～400V with the duty cycle in the instantaneous high voltage pulse signal． The experimental results show that the pulse signal is stable and reliable，and the output ripple is in the range of 0．5% or less，to meet the needle-free injection of piezoelectric power supply requirement．

Keywordsneedle-free injection; pulse power supply; adjustable voltage; adjustable frequency

Research on Integrated Lamb Wave Structural Health Monitoring Technology Based on the Synergism of Active and Passive Methods

WANG Qiang， HUA Jie

( College of Automation，Nanjing University of Posts and Telecommunications Nanjing，210046，China)

AbstractActive and passive monitoring technology based on Lamb wave is one of the hot points to research on structural health monitoring( SHM) ，but they have been applied independently． The analysis of the interaction and complementarity is conducted based on active and passive Lamb wave monitoring system，according to the advantages and disadvantages of the active and passive monitoring system． Their cooperative working mechanism is proposed by combining passive monitoring triggering with active intermittent scanning，setting active monitoring mechanism and fusing active and passive monitoring information． In addition，a hardware implementation of the active and passive integrated system is given and a software platform of real-time monitoring is built． The experimental results show that the active and passive cooperative technology and their system are well integrated with the active and passive monitoring information to improve the monitoring efficiency，monitor precision and reduce the system power consumption．

Keywordsstructural health monitoring; active monitoring based on Lamb wave; passive monitoring based on Lamb wave; the cooperative working mechanism; integrated technology

Experimental Study and Analysis of Ice-Induced Vibration of Offshore Platform with Rocking Column

LIU Feifei1，2， ZHANG Jigang1，2， SU Rui3， HAN Yongli1，2

( 1．College of Civil Engineering，Qingdao University of Technology Qingdao，266033，China) ( 2． Cooperative Innovation Center of Engineering Construction and Safety in Shandong Blue Economic Zone Qingdao，266033，China) ( 3． Zhongyin Estate Jinan，250101，China)

AbstractPlatform with rocking column is a new style structural system which can effectively control the dynamic responses of the offshore platform under ice loads． Combined with energy dissipation devices，the new system can 220 Journal of Vibration，Measurement ＆ Diagnosis Vol．39 have a good energy dissipation ability． This paper optimizes the schemes to research the influence of number and location of link rods and the diameter of rocking column with ANSYS software． The results show that link rods and rocking column have great influence on vibration control effect． The more the link rods and larger the rocking column are，the better vibration control effect will be． Considering the economy of structure and contact area of rocking column and marine，scheme three，four connecting rods and 360 mm rocking column，has been chosen． 1 ∶ 10 scale models，offshore platform and platform with rocking column，have been designed and produced on the base of JZ20-2． The results show that the offshore platform with rocking column is an effective way to reduce vibration．

Keywordsoffshore platform; ice-induced vibration; link rod; damping effect; offshore platform with rocking column

Adaptive Non-local Means with Applications in Fault Detection of Rolling Bearings

TANG Xiaohong1， HU Junfeng1，2， XIONG Guoliang1， ZHANG Long1

( 1． School of Mechatronics ＆ Vehicle Engineering，East China Jiaotong University Nanchang，330013，China) ( 2． Institute of Science and Technology，China Railway Nanchang Group Co．，Ltd Nanchang，330002，China)

AbstractAs known，it is essential to carefully tune the parameters of non-local means ( NLM) in order to take it into full play． The adaptively determination of NLM's parameters for a signal of interest has not been reported so far，which will significantly weaken the NLM in bearing fault diagnosis． Aiming at such a dilemma，a novel fault diagnosis method for rolling element bearings is proposed based on non-local means with particle swarm optimization ( PSO) ． PSO algorithm is used to obtain optimal values of parameter λ，M and P with a superior performance with respect to global optimization and convergence speed． Then an optimalfilter is acquired with the resultant optimal parameters，which can suppress noises and enhance cyclic impact feature hidden in vibrations of faulty bearings after filtering． Finally，fault diagnosis can be achieved by means of the envelop spectrum of the filtered signal． The viability of the proposed method is demonstrated through a series of simulation data and experimental data．

Keywordsnon-local means; particle swarm optimization; parameter optimization; fault diagnosis

Wind Field Characteristics of Large Span Membrane Structure Based on Field Measurement

JIANG Lei1， LI Jinhua2， LI Chunxiang1

( 1． Department of Civil Engineering，Shanghai University Shanghai，200444，China) ( 2． Department of Civil Engineering，East China Jiaotong University Nanchang，330013，China)

AbstractIn this paper，near-surface wind field characteristics，wind pressure characteristics and non-Gaussian characteristics of a long-span membrane structure under strong wind are analyzed based on measured data． The multi-point synchronous wind pressure measurement of the large span membrane structure is carried out in this project． Based on these data，the mean wind speed，the mean wind direction，longitudinal and lateral fluctuating wind velocity，gust factor，turbulence intensity，wind pressure coefficient，wind pressure dependency，probability density distribution，high-order characteristic statistics，power spectral density and other parameters are obtained． The results show that the edge of the membrane has obvious non-Gaussian characteristics under the strong wind，and it is a super-Gaussian process with the kurtosis over three; The up-and-down wind pressure is negatively correlated; The amplitude of the low-frequency component of the measured wind pressure is larger，and the time interval of continuous impact of wind load on each position of the membrane structure is similar． No．

Keywordsfield measurement; long-span membrane structure; wind field characteristics; wind pressure characteristics; non-Gaussian

Study on Prognosis and Health Management of the Space Launch Site Gas System

HU Qingzhong1，2， CHU Fulei1

( 1． Department of Mechanical Engineering，Tsinghua University Beijing，100084，China) ( 2． Key Laboratory for the Space Launching Site Reliability Technology Xichang，615000，China)

AbstractIn order to solve the problem of the health status of single sample equipment，a new method of health management and forecasting based on hidden Markov is proposed． The method uses the equipment monitoring data to construct the hidden data． The Markovian health assessment model is used to simulate the prediction accuracy of different observation sequences and different observation times to determine the optimal model parameters． Then， the real-time data is substituted into the model，and the results are calculated from the model to determine the health of the equipment． Finally，the current data and historical data are fitted to predict the safe and reliable life of the system． The method can effectively solve the health assessment of single-sample multi-state equipment．

Keywordshidden Markov models; condition prognosis; health management; the space launch site

Research on Critical Friction Force and Critical Rotation Speed of Electrode Wire

WANG Min1，3， MA Gangjian1， CAO Pengjun1， LIU Jianyong2，3

( 1．Beijing Key Lab of Advanced Manufacturing Technology，Beijing University of Technology Beijing，100124，China) ( 2．Beijing Institute of Electro-Machining Beijing，100191，China) ( 3．Beijing Key Lab of EDM Technology Beijing，100191，China)

AbstractThe unproperly control of friction force between the electrode wire and director tends to break the electrode wire and exacerbate the vibration of electrode wire in the electrical discharge micro-hole machining． In the light of this problem，the electrode wire is simplified to the Euler-Bernoulli beam to establish the calculation model of the critical friction force and analysis model of its inherent mode． The law between the electrode wire's length and the friction's influence on the natural frequency of the transverse vibration of the electrode wire is analyzed by using the finite element method． The critical frictional force of electrode wire with a diameter of 0．19 mm is calculated． The critical speed of the micro-feed rotary axis is further determined． The conclusion can be used to guide the selection and optimization of process parameters in the process of electrical discharge micro-hole machining．

Keywordselectrical discharge micro-hole machining; electrode wire; critical friction force; critical rotation speed

Performance Evaluation of Tightening Equipment Based on Information Entropy and Lempel-Ziv

FAN Guoliang， LI Aiping， LIU Xuemei， GU Jiawei， XU Liyun

( School of Mechanical Engineering，Tongji University Shanghai，201804，China)

AbstractThere are quality issues such as the stochastic volatility of tightening performance and the decline of the tighten quality stability in the operating process in tightening equipment． For the quantitative characterization of the degree of performance stochastic volatility and disorderly state，information entropy and Lempel-Ziv algorithm complexity of both indexes are applied respectively in this approach to characterize the performance． First，the tightening performance indicators are divided into several states，and the mathematical model of the tightening performance complexity is established based on information entropy theory in order to quantify the random fluctuations extent of tightening performance． Meanwhile，the performance complexity of tightening equipment is also measured based on the Lempel-Ziv algorithm，which gives an approach to describing the disorder of the performance． Finally， the proposed approach is used in an example and the torque and angle data are comparatively analyzed to verify the validity of the proposed approach in the example． The results show that the torque and angle indicators consistently reflect similar trends in equipment degradation． The evaluation results of the information entropy and Lempel-Ziv algorithm describe some differences in the operation process． The performance degradation of the tightening equipment is measured from two dimensions of stochastic volatility and disorderly state．

Keywordsinformation entropy; Lempel-Ziv; complexity; tightening equipment; performance evaluation

Nonlinear Resonance of Mini Type Large Transmission Ratio Movable Tooth Drive System

LI Chong1，2， XING Jichun3， FANG Jiwen1，2， ZHAO Zhong1，2

( 1． School of Mechanical Engineering，Jiangsu University of Science and Technology Zhenjiang，212003，China) ( 2． Jiangsu Provincial Key Laboratory of Advanced Manufacturing for Marine Mechanical Equipment， Jiangsu University of Science and Technology Zhenjiang，212003，China) ( 3． School of Mechanical Engineering，Yanshan University Qinhuangdao，066004，China)

AbstractIn order to apply the movable tooth drive in precision drive field，a mini type large transmission ratio movable tooth system is designed． Based on an elastic dynamic theory of planetary gear drive，the dynamic model of movable tooth system is established． Considering the nonlinear effect caused by the changing of meshing tooth number， the nonlinear dynamic equations of the movable tooth system are built． The nonlinear amplitude-frequency relationship and resonance equations are deduced with the harmonic balance method and the the perturbation method． Besides，the amplitude-frequency curve changes with parameters and the resonance response laws under different multiplicity frequency are analyzed with the two sets given parameters． Results show that the damping coefficient ζ and the amount of meshing movable teeth f have a large impact on an amplitude-frequency curve，and the system resonance is prominent when ωe≈ω1 and ωe≈1 /2ω1 ． So，in order to reduce vibration and improve stationarity of the system，a small number of the movable tooth and small offset of wave generator is necessary． The results lay a theoretical foundation for modifying the structure and improving transmission efficiency of the movable tooth system．

Keywordslarge transmission ratio; movable tooth drive; nonlinear resonance; harmonic balance method; the regular perturbation method

The Stability Analysis of Deploying Cantilever Beam

LIU Ming1， YANG Xiaodong2， ZHANG Wei2， QIN Chaohong3

( 1． Institute of Advanced Structure Technology，Beijing Institute of Technology Beijing，100081，China) ( 2． Beijing Key Laboratory of Nonlinear Vibrations and Strength of Mechanical Engineering， Beijing University of Technology Beijing，100124，China) ( 3． Science and Technology on Reliability and Environment Engineering Laboratory，Beijing Institute of Structure and Environment Engineering Beijing，100076，China)

AbstractThe stability of deploying cantilever beam in the uniform speed case is studied． The governing equations are solved numerically to obtain the tip displacement of the deploying cantilever beam． Two types of methods to determine the stability of such a time-varying parameter system are proposed，namely，the instantaneous eigenvalue method and the stiffness matrix method． The eigenvalues are obtained to analyze the instability by means of studying the real and imaginary parts of the eigenvalues． The negative stiffness occurs while the beam in its unstable state and the features of instability also could be reflected by the changes of stiffness with time． Taking one order and five order truncation for the governing equations respectively，we compare the results of the two cases and find that their results have a good agreement．

Keywordsdeploying cantilever beam; eigenvalue; natural frequency; stiffness; stability

Hydroelastic Simulation Mode of Weak Layered Structure of Roller Compacted Concrete Dams

MA Bin1， ZHAO Zhao1， HU Jianchao2

( 1． State Key Laboratory of Hydraulic Engineering Simulation and Safety，Tianjin University Tianjin，300350，China) ( 2． China Water Resources Beifang Investigation Design ＆ Research Co．，Ltd Tianjin，300222，China)

AbstractThis paper summarizes the features of the layered structure of the roller compacted concrete dam，which was needed for the fine simulation study of the flow-induced vibration of the roller compacted concrete dam． Besides， based on the hydroelastic model test，the simulation method of the layered weak structure of the roller compacted concrete dam is studied in depth，then six scaling criteria that the simulation of the hydroelastic model with rolled layered structure need to meet were presented，and three kinds of adhesion simulation methods of the layered structure are also put forward． Meanwhile，the vibration response signals and frequency response functions for five sets of simulated specimens are analyzed on account of the principle of frequency response function，and the dynamic response characteristics of specimens under different simulation methods are also evaluated． The simulation results show that the mode with materials of milling rubber，vulcanized rubber adhesive，thin low elastic modulus rubber， vulcanized rubber adhesive and milling rubber from the bottom to the top is in accordance with the theoretical laws．

Keywordsroller compacted concrete dam; layered structure; hydroelastic model; frequency response function;dynamic characteristic

Fast Sparse Decomposition and Two-Dimensional Feature Encoding Recognition Method of Diesel Engine Vibration Signal

WANG Xu， YUE Yingjuan， CAI Yanping

( College of Science，Rocket Force Engineering University Xi'an，710025，China)

AbstractIn view of the interference of cross-term in diesel engine vibration signal time-frequency distribution and the difficulty in feature extraction，a new diesel engine intelligent fault diagnosis method based on rapid vibration signal sparse decomposition and two-dimensional time-frequency feature encoding recognition are proposed． First，a modified matching pursuit method called adaptive matching pursuit ( AMP) whose dictionary can be updated according to the residual signal adaptively in the decomposition is put forward to obtain the vibration time-frequency images with good time-frequency aggregation． Then，the signals are decomposed into a series of atoms based on AMP algorithm and the time-frequency distribution of the original signals are obtained based on the Wigner-Ville distribution of these atoms． The feature coding of the time-frequency image amplitude matrix is captured using a twodirectional two-dimensional NMF ( TD2DNMF) algorithm，which can acquire the low dimensional characteristics contained within the higher dimensional time-frequency image． Finally，the nearest neighbor classifier is used to realize the automatic classification of time-frequency image recognition． The proposed method is applied to extract the fault features from four different state diesel engine valve faults，and the results verify that this method works well in eliminating the interference of cross terms in diesel engine vibration signal time-frequency distribution，and it improves the traditional image characteristic parameter extraction method of pattern recognition，the quick and effective fault diagnosis of diesel engine valve is realized by this proposed method．

Keywordsdiesel engine; matching pursuit; two-dimensional non-negative matrix decomposition; feature coding; time-frequency representation

Design and Encapsulation of Capacitive Micromachined Ultrasonic Transducer Linear Array for Underwater Detection

ZHANG Rui1，3， PAN Lihu1， CHEN Lichao1， ZHANG Yongmei2， XUE Chenyang3， ZHANG Wendong3， HE Changde3

( 1． College of Computer Science and Technology，Taiyuan University of Science and Technology Taiyuan，030024，China) ( 2． College of Computer Science and Technology，The North China University of Technology Beijing，100144，China) ( 3． Key Laboratory of Instrumentation Science ＆ Dynamic Measurement， Ministry of Education，The North University of China Taiyuan，030051，China)

AbstractA low frequency capacitive micromachined ultrasonic transducer ( CMUT) array is presented to detect underwater． Based on the analysis of CMUT array structure and work principle，the directivity expressions of CMUT element and the one-dimensional array is established combined with the array composite structure，the geometric parameters are determined in view of the influence on the directivity of CMUT array． According to the application requirement of CMUT underwater detection，the paper studies underwater packaging methods of CMUT array complete the CMUT array water sealing through package structure design and packaging material selection． At the same time，the paper develops a CMUT array performance test scheme and sets up the corresponding test and detection system． The test results show the low-frequency CMUT has better detecting directivity，the -3 dB main beam width and maximum sidelobe level for CMUT array are respectively 5° and -13．5 dB，and the CMUT array can realize No．1 Abstracts of Vol．39 No．1 in English 225 clear underwater detection within the scope of 1m． The experiment results show the proposed design and encapsulation method is reasonable，and provide the design basis for improving the underwater detection performance of CMUT array．

Keywordscapacitive micromachined ultrasonic transducer; array design; array packaging; underwater detection

Roadheader Anomaly Detection Method Based on VSAPSO-BP Under the Single Category Learning

YANG Jianjian， TANG Zhiwei， WANG Xiaolin， WANG Zirui， WU Miao

( School of Mechanical Electronic and Information Engineering，China University of Mining and Technology ( Beijing) Beijing，100083，China)

AbstractTo solve the problem of missing fault data and dividing fault degree in roadheader rotary table anomaly detection，a novel anomaly detection method based on variation self-adapting particle swarm optimization ( VSAPSO) BP neural network under the single category learning is proposed． Using support vector data description ( SVDD) to train the healthy data，constructing a non-healthy sample dataset based on the experience in the field， the non-healthy sample data is divided into fault critical data and fault data based on the recognition rate of SVDD for non-healthy sample datasets，and the variation self-adapting particle swarm optimization algorithm is proposed， the VSAPSO-BP neural network is constructed to detect healthy data，fault critical data and fault data，the detection accuracy is 91．7%，compared with the traditional PSO-BP neural network，VSAPSO-BP neural network has a higher accuracy and stability． The results show that the abnormal of roadheader rotary table can be detected accurately and effectively by using anomaly detection method based on VSAPSO-BP neural network under single learning， this method has a high application value．

Keywordsroadheader rotary table; anomaly detection; support vector data description ( SVDD) ; particle swarm optimization algorithm; BP neural network

Feature Extraction of Rolling Bearing's Slight Fault of SPPCS CEEMD Based on HLS-SVDR

XU Bo1，2， ZHOU Fengxing1， MA Yajie1， YAN Baokang1， LI Huipeng1，2

( 1．School of Information Science and Engineering，Wuhan University of Science and Technology Wuhan，430081，China) ( 2． School of Electronic Information，Huanggang Normal University Huanggang，438000，China)

AbstractComplementary ensemble empirical mode decomposition ( CEEMD) can deal with non-stationary random signals very well，but there are still some shortcomings，such as the fitting overshoot /undershoot and end effects problems． A new method for solving the exiting problem that is shape-preserving piecewise cubic spline ( SPPCS) CEEMD based on homotopy least squares-support vector double regression ( HLS-SVDR) is proposed in this paper， and to achieve correct and efficient EMD decomposition of signals． Firstly，the SPPCS is used to eliminate the fitting overshoot /undershoot problem in the process of structuring the upper and lower envelope curve，and valid envelope curve can be obtained． Then，the HLS-SVDR is introduced to predict and replace the left and right values at both ends of the mean values of the upper and lower envelopes of extreme points of each layer signals for restraining the end effects． Lastly，the proposed method is applied to analyze the case of the feature extraction of rolling bearing's slight fault． The experimental results indicate that the proposed method can effectively and accurately extract the rolling bearing' s slight fault feature． A complete CEEMD algorithm can keep the original characteristics of 226 Journal of Vibration，Measurement ＆ Diagnosis Vol．39 CEEMD，and also effectively restrain the fitting overshoot /undershoot and end effects problems．

Keywordscomplete complementary ensemble empirical mode decomposition; overshoot /undershoot; end effects; shape-preserving piecewise cubic spline ( SPPCS) ; homotopy least squares-support vector double regression ( HLS-SVDR) ; slight fault feature extraction

Analysis of Longitudinal and Torsional Pendulum Coupling Vibration of Scraper Conveyor Under Material Loading Condition

LIU Zhixiang， XIE Chunxue， MAO Jun， XIE Miao

( Research Institute of Technology and Equipment for the Exploitation and Utilization of Mineral Resources，Liaoning Technical University Fuxin，123000，China)

AbstractIn order to improve the operational reliability of scraper conveyer，the coupling vibration characteristics between longitudinal and torsional pendulum of scraper conveyor are studied． Based on Voigt model and point-topoint tension method，the torsional vibration analysis model of scraper chain system is established． The influence area and attenuation characteristic of torsion pendulum vibration under material loading condition are studied． Based on the premise of solving reliability and precision，the maximum number of scraper plates of torsion pendulum vibration units in different sections along the line is determined，and a torsional pendulum vibration abbreviated model is constructed． The dynamic model of longitudinal and torsional pendulum coupling vibration of scraper chain system is established to study the longitudinal and torsional vibration characteristics of scraper chain system under load excitation． Theoretical and experimental studies show that: The maximum fluctuation of the speed and the tension of the scraper are 119．5%and 78．6%，respectively，in imposition of incentives caused by cargo incentive． The tension difference of two chains in the load excitation section is up to 8．6%，and torsion vibration caused by load excitation is more obvious under no material circumstances in the initial time．

Keywordsscraper conveyor; torsional vibration; longitudinal vibration; material loading

Test Research on Plugging Effect of Open Pipe Pile in Sand Based on FBG Sensing Technology

WANG Yonghong1，2， LIU Junwei 1，2， ZHU Na1， ZHAO Guoxiao1， WANG Mingming1

( 1． School of Civil Engineering，Qingdao University of Technology Qingdao，266033，China) ( 2． Cooperative Innovation Center of Engineering Construction and Safety in Shandong Blue Economic Zone Qingdao，266033，China)

AbstractIn order to explore the applicability of fiber grating sensing technology in the process of pipe pile penetration for sandy soil，plugging effect test of the double-walled opening model pipe pile under static pressure pile is tested in a large-scale model test chamber，using a sensitized micro-fiber grating sensor． The height of the experimental model pipe pile is 1065 mm，and the thickness is 20 mm． Moreover，the material of model tubes is aluminum and the pipe pile penetrates into the compact sand． 26 fiber Bragg grating ( FBG) measuring points are arranged symmetrically along the internal and external pipes． The plugging height and strain data are collected by changing the shape of the pile shoe． The plug height，medial and lateral friction and other penetrating characteristics of the pipe pile are analyzed，and the plugging effect under static load is studied． The results show that FBG is suitable for the test of plugging effect of double-walled open pipe piles，which can accurately reflect the strain of No．1 Abstracts of Vol．39 No．1 in English 227 pipe piles and penetration characteristics of the medial and lateral friction．

Keywordsfiber Bragg grating sensor; sand; pipe pile; plugging effect; test analysis

Excitation Response Characteristics of Ball Screw Feed Drive System and Cosine-Like Jerk Motion Profiles

LUO Liang1， ZHANG Weimin1，2， Jürgen Fleischer3，4

( 1．School of Mechanical Engineering，Tongji University Shanghai，201804，China) ( 2． Sino-German College for Postgraduate Study，Tongji University Shanghai，201804，China) ( 3． Advanced Manufacturing Technology Center，Tongji University Shanghai，201804，China) ( 4． wbk Institute of Production Science，Karlsruhe Institute of Technology Karlsruhe，76131，Germany)

AbstractThe motion commands to feed drives constitute a major source for excitation of the machine tool feed drive vibrations． Firstly，based on the lumped mass model of ball screw feed drive system，a theoretical model between servo motor torque excitation and system response is established． The co-relation between acceleration profile of motion command and the excitation response characteristics of feed drive system is analyzed． The discontinuous curve at the start point and the end point of jerk profiles in the existing motion profiles leads to frequency contents， which may cause the feed drive into vibration． Secondly，a Cosine-like Jerk motion profile is proposed，which eliminate the discontinuous jerk curve and reduce the excitation on the feed drive system． Finally，taking a ball screw feed drive test bench as the research object，the lumped mass model is established and experimentally verified． On this basis，a simulation model to study the excitation characteristics of motion profiles is established，and then the excitation characteristics of motion profiles are compared and analyzed． Simulation result shows that，Cosine-like Jerk motion profiles has the smallest excitation characteristics，the power density of the second order nature frequency of the work table response is only about 1 /10000 of the Jerk-limited motion profiles and about 1 /100 of the sine Jerk profiles．

Keywordsball screw feed drive system; lumped mass model; trajectory generation; cosine-like jerk

Detection of Weak Impulse Signal Under Strong Noise Background

LIU Yunjiang， WANG Fuzhong， LIU Lu

( School of Science，Tianjin Polytechnic University Tianjin，300387，China)

AbstractIn view of the random impulse of the mechanical environment noise and the shortcoming of traditional measurement index for recognizing the impact signal of the mechanical fault，a new criterion ( Kurtosis-Intercorrelation combined index，abbreviated as KI) using as the basis for detecting the impact signal，which is constructed with kurtosis index and cross correlation coefficient，is proposed，and the detection of impact signal in asymmetric bistable system is studied with utilizing Levy noise as background noise． Firstly，the transition density function of particles and the construction method of KI in asymmetric bistable system driven by Levy noise are theoretically analyzed． Secondly，the variation trend of the output KI value of the system with the system parameter a and the asymmetric factor C is studied respectively，when the Levy noise characteristic index α is 1．5． Finally，the method is applied to the detection of the actual mechanical fault impact signal． The results of simulation and experiment show that，compared with the kurtosis index as an impact signal detection basis，KI can increase the signal characteristic amplitude of the output of the system more than one times． The output KI value of the system increases with the C first and then decreases． When the asymmetric factor C is 0．54，the output KI value of the system is increased by 7． 228 Journal of Vibration，Measurement ＆ Diagnosis Vol．39 02% than that of when C is 0． The engineering example data proves that the method can extract the time-domain and frequency domain feature information of fault signal effectively，and it can be applied to the actual mechanical fault detection．

KeywordsLevy noise; asymmetric bistable system; stochastic resonance; impact signal

3-DOF Compliant Precision Positioning Stage Based on Piezoelectric Actuators

ZHANG Quan1， DONG Yichong1， REN Guang1，2， SUN Yi1，PENG Yan1， PU Huayan1， LI Xiaomao1

( 1． School of Mechatronic Engineering and Automation，Shanghai University Shanghai，200072，China) ( 2． School of Mechanical and Electric Engineering，Guangzhou University Guangzhou，510006，China)

AbstractIn this paper，a novel 3-PRR planar parallel compliant stage driven by piezoelectric actuators is proposed． In order to eliminate the assembly clearance and friction of the traditional joints，the semi-circular flexure hinge and the right-angle flexure hinge are chosen as the flexible rotation joint and flexible prismatic joint in each chain of the stage，respectively，and then the finite element analysis is used to analyze the stiffness of the two types of hinges． In order to achieve larger workspace in a given size，a lever displacement amplification mechanism is planned in each branch． Based on the " Pseudo-rigid Body Model Method"，the kinematic model of the compliant positioning stage is established． Then the finite element analysis of the compliant parallel stage is performed using ANSYS software，and its static characteristics are obtained． Finally，the 3-PRR planar parallel compliant stage experimental test system is set to verify the kinematic model． The maximum error results between the theoretical kinematic analysis，the finite element analysis and the experimental tests in x，y，and φp directions are 10．81%，9．66% and 9．79%，respectively，which validate the correctness of the kinematic model．

Keywordsprecision positioning stage; the pseudo-rigid-body model; piezoelectric actuator; flexure hinge

Vibration Characteristics of Equipment Cabin Bottom Plate

ZHANG Fubing1， LIU Chaotao1， WU Pingbo1， SHI Huailong1， WU Xingwen1， ZHU Haiyan2

( 1． State Key Laboratory of Traction Power，Southwest JiaoTong University Chengdu，610031，China) ( 2． School of Mechatronics Engineering，East China Jiaotong University Nanchang，330013，China)

AbstractIn order to optimize the vibration fatigue characteristics of the equipment cabin bottom plate，a rigidflexible coupled multi-body dynamic model is established，and the relationship between the vibration of the key position of the floor and the vehicle speed is analyzed under the Wuguang spectrum． It is found that the overall vibration of vehicle equipment cabin bottom plate is increasing with the speed，but at 250 km/h，the longitudinal acceleration amplitude is larger than 300 km/h． Then according to the dynamic simulation results，the loads is extracted and the finite element strength analysis is performed． The maximum stress of the whole bottom plate and the maximum stress around the hole are obtained． The rolling table test data is consistent with the simulation results． Finally， the bottom plate is optimized to thicken the plate thickness． By comparison，the overall maximum stress after optimization is reduced from 8．78 MPa to 4．79 MPa，and the maximum stress around the hole is reduced from 1．65 MPa to 0．95 MPa． The strength performance of the bottom plate has been greatly improved．

Keywordsvehicle system dynamics; modal analysis; orbital excitation; equipment cabin bottom plate

Temperature Field Analysis and Experiment Research of Ultrasonic Consolidation Area

WANG Yin1， CAO Jun1， LIAO Mengjiao1， XIAO Zhongyang2， ZHANG Huixia2， HUANG Weiqing3

( 1．College of Mechanical Engineering and Automation，Huaqiao University Xiamen，361021，China) ( 2． College of Aerospace Engineering，Nanjing University of Aeronautics and Astronautics Nanjing，210016，China) ( 3． School of Mechanical and Electrical Engineering，Guangzhou University Guangzhou，510006，China)

AbstractTemperature is an important factor affecting the quality of ultrasonic consolidation． Due to the difficulty of direct measurement of the temperature in the consolidated area，this research illustrated the influence of process parameters on the consolidation temperature through numerical simulation． Firstly，based on the Hertz contact theory and the Coulomb friction law，the friction work in the consolidation area is analyzed，and the heating model of the consolidation area is established． Secondly，the three-dimensional thermal conduction finite element model of titanium aluminum foil is established，and the influence of the main process parameters on the temperature field distribution in the consolidation area is analyzed． Finally，in order to verify the validity of the model，a temperature test platform for ultrasonic consolidation is established，and the temperature of consolidation is measured by means of embedding thermocouple in the substrate． It is found that the experimental results are basically consistent with the trend of the numerical simulation results，which confirms the validity of the model．

Keywordsultrasonic consolidation; finite element; temperature field; heat conduction

Multivariable Empirical Wavelet Transform for Multipoint Forecasting After Sensor Fault

LI Chunxiang， ZHANG Jiali

( Department of Civil Engineering，Shanghai University Shanghai，200444，China)

AbstractIn order to effectively decrease the loss caused by the multipoint fault of wind speed sensors or wind pressure sensors，and to reduce the complexity of computation and the difficulty of the engineering application，a model needs to be proposed to recover the missing data at the same time． As the traditional multi-channel signal diagnosis uses multivariate empirical mode decomposition ( MEMD) ，the multivariable empirical wavelet transform ( MEWT) is proposed to restore the multipoint missing data synchronously． In practical application，the multipoint signals are decomposed into a series of modes at the same time，and then the kernel-based extreme learning machine ( KELM) is used to predict，and the cuckoo search ( CS) algorithm is used to optimize the regularization parameters of the model and the kernel parameters． For multi-step forecasting，the traditional recursive strategy is replaced by the multiple-input multiple-output ( MIMO) strategy． The actual measured multipoint wind pressure on the building surface and the measured multipoint data of the downburst are used to verify the feasibility of the model． Compared with the noise assisted multivariate empirical mode decomposition kernel-based extreme learning machine ( NA-MEMD-KELM-CS) ，the result shows that the proposed model can recover signals simultaneously with high accuracy．

Keywordssensor fault; kernel-based extreme learning machine; cuckoo search algorithm; multivariable empirical wavelet transform; synchronous multi-step prediction

A Kind of Non-resonant Linear Piezoelectric Motor with Nanometer Stepping Characteristics

CHEN Xifu1， LI Ming1， LU Qian1， HUANG Weiqing2

( 1． School of Mechanical Engineering，Yancheng Institute of Technology Yancheng，224051，China) ( 2． School of Mechanical and Electrical Engineering，Guangzhou University Guangzhou，510006，China)

AbstractThe non-resonant friction-driven linear piezoelectric motors have the advantages of structural simplicity and good running stability，but they can only obtain micron-level positioning accuracy． In order to achieve the nanolevel positioning accuracy，the precise stepping motion of the motor is realized by precisely controlling the positive pressure and relative speed between the motor stator and mover． Firstly，on the basis of studying the principle of stepping motion of the motor，the driving foot with the characteristics of normal vibration frame is is designed for independent decoupling of normal vibration and tangential one at the driving end． Then，the finite element method is employed to optimize the parameters of the stator's driving foot，and the main structural dimensions of the stator driving foot are determined． Finally，the motor prototype is fabricated and the vibration characteristics of the motor stator and the mechanical characteristics of the motor system are experimentally investigated． The experimental results of the stator' s vibration characteristics show that the motor can make different driving characteristics in the driving phase and the return phase in the range of 1～400 Hz． The difference of the moving displacement of the motion in the above two motion phases is the motor step，which results in a smaller displacement resolution． The experimental results of the mechanical output characteristics show that the motor has micro- and nano-stepping motion characteristics in the range of 1～400 Hz，and the displacement resolution of the motor is up to 11 nm in 1～30 Hz． In summary，the motor can achieve micro-nano positioning accuracy within 400 Hz and the maximum motor velocity is up to 63．3 μm/s．

Keywordslinear motors; piezoelectric actuators; stepping motion; nanoscale resolution; non-resonance