15 December 2014, Volume 33 Issue 23
    

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  • Hu Changbin;Sun Zenghua
    . 2014, 33(23): 1-8.
    Abstract ( 326 ) Download PDF ( 360 )   Knowledge map   Save

    Concrete pavement slab may get a significant built-in curling for dry shrinkage and built in temperature gradient during early age. Effection of built-in curling of slab on dynamic load and riding comfort were analyzed based on quarter vehicle vibration model and road-vehicle dynamic interaction analysis method.The results show that built-in curling has more effects on roughness and random dynamic load of higher-grade pavement, and the main effects on road roughness and vehicle random dynamic load parameters relative to frequency of (slab length/speed). Built-in curling and environmental temperature gradient overlay will produce upward or downward curling, slab upward curling have a larger influence on the pavement roughness and random dynamic load, down warping has little effect. sensitivity analysis show the riding comfort, pavement grade, vehicle parameters and speed have more significant effectiton than curling. three roll shaft constuction built-in curling shape have a higher effect than built in curling. Effective built-in temperature difference keep below -10 ℃ may lead to a good performance of pavement slab.

  • Ma Wei-Meng Wang Jian-Jun
    . 2014, 33(23): 9-14.
    Abstract ( 334 ) Download PDF ( 354 )   Knowledge map   Save

    Dynamic analysis method of anisotropic asymmetric rotor-bearing system based on 3D finite element method was presented. The system mass, stiffness and coriolis force matrices expressed in the rotating coordinate system were generated by ANSYS. Time-varying bearing stiffness in the rotating coordinate was then obtained by coordinate transform. The differential equations of motion of the system were generated by applying constraints and time-varying bearing stiffness to the system matrices using the corresponding relationship between node number and column index of the matrices. Floquet theory and Hill infinite determinant method were adopted to solve the differential equations and frequency characteristics and stability of the system were obtained. The proposed method was validated based on a literature model, and the proposed method was applied to the dynamic analysis of an industrial rotor considering the anisotropic asymmetric characters.

  • Song Tao;Tang Baoping;Deng Lei
    . 2014, 33(23): 15-19.
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    The common batch manifold learning algorithms can’t achieve dimensionality reduction rapidly of additional samples with the learned manifold structure, the incremental orthogonal neighborhood preserving embedding (IONPE) manifold learning algorithm was proposed. It achieves dynamic incremental learning for the additional samples with the block processing idea based on orthogonal neighborhood preserving embedding. Firstly, select some overlapping points from the original samples and add them to the additional samples; Secondly, get the subset of low-dimensional embedding coordinates of additional samples by ONPE not depending on the original samples; Finally, based on the principle of minimizing the differences of the overlapping point coordinates, the low-dimensional embedding coordinates of the additional samples were integrated into the original samples by rotating, shifting and scaling transformation. The fault diagnosis case of the gearbox confirmed that the IONPE algorithm has good incremental learning ability. It improves the processing efficiency of the additional samples while inheriting the superior clustering performance of ONPE.

  • Pan Xin;Wu Haiqi;Gao Jinji
    . 2014, 33(23): 20-23.
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    Vibrations on grinding machines are primarily caused by the unbalance in the grinding wheel. A new type of liquid-transfer active balancing device is proposed to adjust the balancing state of grinding wheel and increase grinding accuracy. In the balancing system, compressed air is used for driving balancing liquid to transfer between two opposite chambers. The distribution of liquid in balancing disk is changed and the grinding wheel is balanced. Balancing performance of the device is analysed .The experiment result demonstrates that the unbalance response is reduced from 10.2um to 0.37um at 5500 r/min and the decrease in amplitude is more than 95%.

  • Yan Yanju;;YU Zhixiang; Li Han;Zhang Qili
    . 2014, 33(23): 24-29.
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    In order to ensure the glass deformation coordinated with cable net, the structure model which included glass panel, cable net, sealant, and spider was established to study the influence of glass panel to the static performance and dynamic characters of cable net. The flow field was simulated considering the buildings around the glass facades. Based on those, fluid-structure interaction analysis was carried out to study the spectrum characteristics, dynamic response of glass facades. Under the average wind load, cable net reaching new equilibrium position, Wind-induced response of structure was researched with frequency domain method. Comparison of two methods results show that under wind load, the structure vibration forced by wind was a narrow band process; the glass stiffness effectively reduced the average displacement and pulse response of the cable net.

  • WANG Ming-yi;JI Hong-li;QIU Jin-hao;ZHANG Chao
    . 2014, 33(23): 30-36.
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    Active stiffness control of plate structure using shape memory alloys is investigated and the layout optimization of actuators on the plate is presented. A FEM model is established to analyze the active control effect and the simulation results were validated by experimental results. The results indicate that the recovery stress of SMA is the main factor in change of structural stiffness. They also show that the effectiveness of this method in stiffness control depends on the temperature, volume ratio, and arrangement of SMA actuators. Furthermore, the layout of SMA actuators is optimized by using a genetic algorithm. The results show that the optimized layout is more effective in stiffness control than the original layout.
  • ZHANG Jin-feng;WANG Wen-jie;FANG Yu-jian;YE Li-ting;YUAN Shou-qi
    . 2014, 33(23): 37-41.
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    In order to investigate the effect of the splitter blades on the unsteady flow and structural dynamic characteristics on the molten salt centrifugal pump, the directly coupled method, considering the interaction of fluid and structural fields, was applied to compare the unsteadiness and structural dynamic characteristics of the pump with and without splitter blades by using the ANSYS CFX 12.1 and ANSYS Workbench. By comparing the results of the unsteady flow and the structural characteristics, some conclusion are drawn: the results of pressure fluctuation and the radical trust are changed greatly, which indicate that the effect of FSI is quite obvious which cannot be ignored; the pressure fluctuation, the radical trust, the maximum equivalent stress fluctuations, the maximum deformation fluctuations, and the equivalent stress distribution and deformation of the pump are decreasing by adding splitter blades, which can prove that the splitter blades can improve the impeller blade loads and the capability of anti-fatigue.

  • CHANG Jun;Gong Wenlong
    . 2014, 33(23): 42-46.
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    Multi-DOFs structural modal parameters identification turns into several SDF structural modal parameters identifications through treating structural output data by Continuous Wavelet Transform. An optimization issue with the objection function of the difference between theoretical formula of wavelet skeleton and the wavelet skeleton calculated from structural output-only data is carried out. The optimal objective value can be gained through searching reasonable modal parameters included in the theoretical formula of wavelet skeleton. And the optimization turns into structural modal parameters identification. Quantum-behaved Particle Swarm Optimization, as a swarm intelligence optimization algorithm, is used in the structural modal parameters identification above to identify the structural modal parameters (frequencies, damp ratios and modal shapes) under ambient excitation just one time. Finally, the modal parameters identification method based on Quantum-behaved Particle Swarm Optimization combined with Continuous Wavelet Transform presented herein is verified by a numerical simulation of a simple-support beam. The results show that methodology herein can effectively identify structural modal parameters under ambient excitation.

  • ZHOU Si-Da; LIU Li; YANG Wu; MA Zhi-Sai
    . 2014, 33(23): 47-52.
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    In cases of output-only modal parameter estimation for operational engineering structures, such as aerospace structures, the non-white excitations result in the non-physical modes, which are not able to be identified. For these cases, the recently developed response-transmissibility-based methods of modal parameter estimation are researched and an improved poly-reference response-transmissibility-based output-only approach of modal parameter estimation is proposed. Firstly, the parametric model of the poly-reference response transmissibility is introduced, which is presented by the left matrix fraction polynomials, the formulations of the least square estimation for unknown parameters are proposed, and the normal equation of the least square estimation is reduced by using the block property of the corresponding Jacobian matrix, which largely decreases the computational costs. Secondly, based on the high-dimensional accompany matric method, the eigenvalue problem of the matrix polynomials has been achieved, which results in the solution of the modal parameters. In addition, the original constraints between the number of loading conditions and the number of references is removed by using the pseudo inverse of matrix. Finally, two numerical examples have validated the proposed method. The results illustrate that the proposed method can estimate the modal parameters very well and has the advantage of avoiding the influence of harmonics, which means that the problem of non-white excitations has been solved.
  • WANG Hong-xia;;GONG Xian-sheng; LIU Wei; PAN Fei;
    . 2014, 33(23): 53-57.
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    A circular wire-cable vibration isolator is designed by adopting independent wire rope loops as elastic damping elements. Owing to its unique structure, the isolator exhibits nonlinear elastic stiffness and asymmetric hysteresis dynamic behavior in the tension–compression mode. In the present study, a modified normalized Bouc-Wen model is proposed to describe the hysteretic behaviour of a circular wire-cable vibration isolator. A two-stage identification method is developed for identifying the model parameters. Periodic loading experiments were carried out to validate the proposed model and identification method. The results verify that the proposed model and identification method are effective for accurate description of asymmetric hysteresis dynamic behavior in the tension–compression mode of circular wire-cable vibration isolator. It establishes the foundation for dynamic design method of circular wire-cable vibration isolator.

  • XU Li-fu;TA Na;RAO Zhu-shi;TIAN Jia-bin
    . 2014, 33(23): 58-62.
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    A 2-D finite element model of human cochlea is established in this paper. This model includes the structure of oval window, round window and basilar membrane, fluid filled with the cochlear duct. In order to study the effects of helicotrema on basilar membrane response, three different dimensions of helicotrema are set up in the FEM. A two-way fluid-structure interaction numerical method is used to compute the response in the cochlea. The influence of the helicotrema is acquired and the frequency selectivity of the basilar membrane motion along the cochlear duct is predicted. These results agree with the experiments and indicate more true results are obtained with appropriate helicotrema size.
  • WANG Xiao;XIE Zhenyu;ZHOU Hongkai
    . 2014, 33(23): 63-67.
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    建立了5 自由度磁悬浮轴承支撑的垂直轴风力发电机转子试验系统,研制了零偏置电流模拟控制器,通过试验方法研究了该控制器对系统动态性能的影响。结果表明,零偏置电流控制方式在显著降低磁悬浮轴承电能损耗的同时仍然能够保证垂直轴风力发电机转子系统稳定运行。
  • ZHANG Shao-feng;LOU Wen-juan;LV Zhong-binDUAN Zhi-yong;HUANG Ming-feng
    . 2014, 33(23): 68-73.
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    The turbulent characteristics of nonstationary strong wind are analyzed based on field measured wind records of 1128-h long, collected at a height of 10 meters over an open flat terrain. According to the assumption that the average wind speed component was deterministic time-varying in a time interval, a nonstationary wind model was proposed and then applied to find its turbulent characteristics. The results were compared with those calculated by a stationary wind model, in which the average wind speed component was assumed constant. It is found that 55% samples of wind records are nonstationary, and the nonstationary wind model is more appropriate for charactering wind speed. The variations of turbulent characteristics for wind speed were studied, and it shows that the turbulent intensity seems to have no significant relationship with wind speed and mainly distributes within 0.16~0.20, a value slightly greater than that given in wind load codes; the gust factor decreases while wind speed increases, the turbulent integral scale the opposite; Davenport spectrum tends to be more accurate to characterize the energy distribution than other wind spectra.
  • Pu Yuxue Zhang Fang Jiang Jinhui Xu Jing Jiang Qi
    . 2014, 33(23): 74-80.
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    Changes of control target area and errors sensor position or other factors may lead to the real-time change of the secondary path in practical engineering. Accurate identification of secondary path transfer function can effectively improve the efficiency of active noise control. This paper proposed a new online secondary path modeling method based on Delay Coefficient Technique. The proposed algorithm derived adjustment rules of the convergence step sizes of active control process and secondary path modeling. Comparing with the traditional algorithms in convergence performance and the computational complexity, the improvement advantages are gotten. The proposed algorithm also introduced an auxiliary noise power scheduling for achieving the adjustment of the additional random noise power to ensure system stability and eliminate its influence on the residual noise as soon as probability. Computer simulations and experiments show that the proposed method gives better performance in convergence and noise reduction than the existing methods.
  • LOU Jiang-lei TANG Jin-yuan
    . 2014, 33(23): 81-86.
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    Based on the CAE/CAT/CAO technology, a method to identify the bearing stiffness of gearbox was proposed, with the combination of finite element modal analysis, experimental modal analysis and Integrated optimization by Isight:1)The finite element analysis modal of gearbox was built by the finite element analysis software of Abaqus, and a spring element was used to simulate the three-dimensional equivalent stiffness of bearing, as well as a design variable; 2) The natural frequencies and vibration modes, containing information of bearing joint interfaces, were acquired by the experimental modal analysis of gearbox, with the LMS modal test and analysis system, and the test frequencies were set as the optimization target;3) The results of finite element modal analysis and experimental modal analysis were in consistent by optimization of the bearing stiffness through the Abaqus integrated by Isight. Analysis results showed that the proposed method consider the flexibility of gear shaft and gear box, had high precision, and there is a good agreement between the finite element model of gearbox after optimization and the test model for the dynamic property.
  • TANG Zhi;PAN Yi-shan;LI Qi;XIAO Yong-hui;ZHENG Wen-hong;MA Xiao
    . 2014, 33(23): 87-91.
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    For the effective prevention or reducing the loss of the rock burst in coal mine, a mine thin-walled component with square folds for rock burst prevention was put forward, the rock burst prevention are embodied in the fracturing process in which the component absorbs the impact energy and space to provide the energy release space for the coal rock .The ABAQUS finite element software was used to simulate the energy absorption properties of different wall thickness and number of modules in axial and compare with the conventional rectangular thin-walled analysis. The Result Indicates that (1)the thin-walled component with square folds have the lower crushing peak load and the higher total energy absorption and specific energy-absorption capability, the rock burst prevention effect is remarkable.(2) reducing the wall thickness of the thin-walled component with square folds and reducing the length to increase the module number of the component in axial all could effectively reduce the crushing peak load , but reduce the total energy absorption and specific energy-absorption capability at the same time. According to the simulation results to select the size of the mine thin-walled component with square folds for rock burst prevention, the experimental study was carried out to prove the accuracy of the simulation. The mine thin-walled component with square folds for rock burst prevention was combined with the existing supporting , which can make it act as hydraulic prop and the bumper bracket of top beam 、mudsill and the two sides etc.

  • HUANG Yi;LIU Hui;XIANG Chang-le;YANG Zhi-gang
    . 2014, 33(23): 92-99.
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    With the improving requirements of the dynamic quality of transmission system, only the eigensensitivities analysis could not satisfying the requirements of dynamic characteristics about transmission system of vehicle. It’s need to turn to response sensitivity research to find guideline for reduce vibration of vehicle transmission system in designing stage. This paper studies the sensitivities of dynamic response with respect to design parameters (such as shaft torsional stiffness, moment of inertia, transmission errors of gear pairs, et al.) The lateral-torsional coupling dynamic model which adopting engine as input source is built up by lumped parameter method. The sensitivity equations are derived from dynamic equations which containing nonlinear terms (such as time-varying mesh stiffness, backlash of gear pairs, mass eccentricity, transmission error et al.). The relative sensitivity of dynamic response with respect to design parameters which then turning into relative sensitivity of force/torque with respect to design parameters are acquired from numerical simulation method. The results of the relative response sensitivities give the theoretical basis of next works which containing dynamic modification, model updating, parameter optimization and so on.

  • YANG Ming-yue SUN Ling-ling WANG Xiao-le
    . 2014, 33(23): 100-105.
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    Classical thin shell theories and modal superposition principle are used to investigate the dynamic response of isotropic circular cylindrical shells with both ends shear diaphragms supported. The contribution of non-radial vibration components and responses of sinusoidal and cosine modes are taken into account. The force, moment and coupling mobility functions of a circular cylindrical shell which simultaneously subjected to harmonic point force and moment excitations are derived. It is shown that non-radial vibration components have remarkable effects on the prediction accuracy for modes and mobility frequency spectrum, and the real parts of coupling mobility functions may be negative. It can provide a theoretical guidance for the vibration and noise reduction of cylindrical shell structures and for designing active and passive vibration isolation systems with circular cylindrical shell foundations.

  • ZHAO Li-juan; LAN Jin-bao
    . 2014, 33(23): 106-110.
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    To study the transmission system of the coal winning machine cutting part, the theory of rigid-flex coupled multi-body system dynamics is applied, a method for determining the model parameters is presented. The transmission system dynamics model of rigid-flexible coupling multi-body contact was built in the RecurDyn software environment and exerted in the MATLAB to calculate the actual condition of the load. In order to optimize the simulation results of the gear , the meshing process is described directly and dynamically and the dynamic equivalent levels of gear stress is calculated under the simulation environment. The problems of large mechanical transmission mechanism with flexible contact simulation are solved and proved in the reliability of virtual prototyping technology, more over periodic fluctuations are revealed for the stiffness excitation and meshing gear transmission system.
  • FANG Ze-ping;WANG Xi-bin;LIU Zhi-bing;CHEN Ming;XU Zong-wei
    . 2014, 33(23): 111-115.
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    A dynamic model for the over-hang part of the micro-endmill is proposed, which comprehensively considered the shear deformations and rotary inertia effect arising from the nature of the micro-endmill by using the theory of Timoshenko beam. The convergence behavior of the built model is analysed, and its accuracy is verified by experiment, and the applicability of the model is proved by comparing with the calculated results from finite element method and the Euler beam theory. Based on the developed model, the effect of the tool tip diameter, tip section aspect ratio and semi-taper angle on the natural frequencies of micro-endmill are studied. The proposed model enables better parametric design and optimization of micro-endmill for excellent dynamic performance.

  • NI De ZHU Ru-peng FU Qiu-ju BAO He-yun LU Feng-xia
    . 2014, 33(23): 116-121.
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    A design method for system parameters of smart spring system with linear viscous damping under harmonic excitation is presented, which can make the smart spring system implement both stiffness and damping control. First, the analytical solutions of frequency response characteristics of smart spring system were deduced by equivalent linear method. Then, the influence of system parameters on the amplitude frequency characteristics of system was analyzed. The results show that the amplitude frequency characteristic curve cluster has a common point for the smart spring system without viscous damping, but the common point will disappear for the system with damping. The main system parameters that affect the amplitude frequency characteristics of system are the mass ratio, stiffness ratio, damping ratio and control parameter. And the system parameters of which affect the size of required actuator force to make the two mass-spring systems become fully coupled are damping ratio and relative damping ratio. Based on the conclusions of foregoing parameter analysis, the selection scope of system parameters of smart spring system was determined and the steps of parameter design were proposed.
  • DONG XiaoMin WANG XiaoLong
    . 2014, 33(23): 122-126.
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    The output damping force of the magneto-rheological (MR) damper will be reduced with the increment of working temperature. As a result, the performance of the MR suspension system will be degraded. On the basis of the theory of heat transfer and nonlinear vibration, the main resonance of the MR suspension dynamic system with slowly varying parameters will be analyzed in this study. The energy differential equations at the working area of an MR damper were established and solved by the numerical method. The modified Bingham model was applied to calculate the output damping force of the MR damper. The nonlinear dynamic equation of the MR suspension system with a slowly varying parameter was formulated. The steady amplitude response of the MR suspension system under the excitation of main resonance was deduced by the averaging method. The calculated results show that the working temperature will be increased with the increment of running time of the MR damper. Consequently, the output damping force of the MR damper will be significantly reduced and the vibration amplitude variation of the suspension system will also be increased. Therefore, the performance of the MR suspension will be degraded.
  • WANG Guan-shi  HU Shi-li; LI Zhi-wen WANG Xing-guang
    . 2014, 33(23): 127-132.
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    The effects of frequency in different range of frequency bands on attenuation coefficient are different. The filter properties of stress wave propagating in intact rock mass within the scope of log frequency are studied through the field test. Based on the shortcoming of common viscoelastic model predicting the relationship between attenuation coefficient and frequency, Maxwell model adopting unsteady viscosity coefficient is established after the unsteady calculation of viscosity coefficient is performed. The filtering effect of improved model is evaluated using waveform correlation coefficient. The study results indicate that intact rock mass have a low pass filter property and unequal interval band-pass property within the scope of low pass filter. The number of band-pass decreases with the increase of propagation distance. Attenuation coefficients of stress wave with frequency change greatly in the transition zone of absorption frequency. The change rule of attenuation coefficient of stress wave propagation in intact rock mass is effectively described using improved Maxwell model containing unsteady viscosity coefficient. The boundary frequency in the transition zone of absorption frequency has negative index relationship with propagation distance. The edge gradient parameter in the transition zone of absorption frequency is approximately constant. The filtering effect of intact rock mass improves obviously using improved Maxwell model with the increase of propagation distance. The waveform correlation coefficient reaches to 0.89 when propagation distance of stress wave is 4.75m. The improved model is capable of describing the properties of intact rock mass.
  • Xu Zhuofei LIU Kai Zhang Haiyan Wang Dan Zhang Minglong Wu Xinyang
    . 2014, 33(23): 133-139.
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    A new fault diagnosis method for rolling and bearing based on empirical mode decomposition and multivariate statistics is proposed. The Hilbert-Huang transform and principal component analysis are used in this method. The vibration signal is decomposed into the basic mode components with EMD and the instantaneous frequency of each component is obtained with a Hilbert-Huang transform. Then calculate the statistical characteristics of the instantaneous frequency and the time domain signal. Analyses the statistical characteristics with PCA in order to reduce the number of dimensions of the feature vector and get the principal component characteristics. Finally, complete the classification of three failure modes in rolling bearing and analyze the relationship between the statistical characteristics and failure modes.
  • OUYANG Huimin ZHANG Guangming WANG Deming MEI Lei DENG Xin
    . 2014, 33(23): 140-144.
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    This paper aims at the residual load sway problem of overhead cranes, and proposes an S-shaped curve trajectory generation method to achieve residual load sway suppression. Firstly, a dynamic model of an overhead crane is derived. Next, an optimal S-shaped curve trajectory that can achieve the shortest transport time and residual load sway suppression is generated by numerical calculation. Finally, comparative simulations and experimental results demonstrate the effectiveness of the proposed method. Therefore, the crane can be precisely and rapidly operated without sensor systems for measuring load sway of the load, consequently, the structure of the crane can be simplified and implementation cost can be reduced.
  • ZHU Xiang;LU Xin-zheng;DU Yong-feng;WANG Qiang
    . 2014, 33(23): 145-149.
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    The derailed train may impact station buildings, which will cause serious consequences. But the corresponding research is still very limited. In the paper, the finite element models of the train, the railway and the ground is built up with nonlinear finite element software. By introducing an artificial obstacle, the train derailment and the attitude of the train after the derailment are simulated. The influence of various friction coefficients of the ground is discussed. The simulation results show that the friction coefficients of the ground will influence the speed and running time after the derailment. Significant pulling and collision between different cars of the train can be observed. The rear cars will push the front cars, which make the train moves in a “snake like” attitude. The train may collide with objects within 6.68m beside the railway.
  • Jin Hong; Jin Shuyun; Chen Changxin; Wang Yan;
    . 2014, 33(23): 150-154.
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    A relative wave crest detecting algorithm base on all the tenses is proposed aiming at how to detect the number of medium layer on multilayer penetration. The algorithm mainly uses time information as a basis for the layer number recognition, then utilizes the polarity of the difference between the wave peak apex and the data points before and after it to preliminary identify the number of the wave peak, then bases on pulse width and fengfeng interval information for number of peaks for further confirmation in order to improve the correction of recognition the number of medium layer. The algorithm is feasible and correct in data processing through simulation and shooting range test. The algorithm provides a new design thought for the penetration layer recognition, does not rely solely on peak, makes full use of time and amplitude information of the signal comparing with the existing absolute threshold comparison method.

  • YAN Xiao-jun Jiang Wei-Kang CAO Cheng
    . 2014, 33(23): 155-159.
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    According to vibration isolation effect of one vehicle powertrain mounting system is insufficient, set natural frequency and decouple rate of mounting system as integrated optimum objective,and used simulated annealing and genetic algorithm (SAGA) to optimize the mounting rates. The optimized results show better natural frequency distribution and higher decouple rate in the major vibration direction. The vehicle vibration isolation test results show the optimized mounting system meet the design requirement.
  • SUN Dongyang CHEN Guoping Wang Tiecheng
    . 2014, 33(23): 160-164.
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    In this paper, the effects on dynamic characteristics of a mechanism with clearance driven by harmonic drive, considering the flexibility of harmonic gear, were investigated. Firstly, the contact model of a mechanism with clearance driven by harmonic drive was established by using the nonlinear spring-damp model. Then, a slider-crank mechanism with clearance was simulated. The result showed that harmonic drive and flexibility of mechanical parts had cushioning effect of collisions for clearance. The cushioning effect was not obvious when the stiffness of mechanical parts was high, while the reduction of stiffness of mechanical parts would result in large deformation during the run which would influence the mechanical properties of the mechanism. It set a theoretical foundation for the use of harmonic drive in mechanisms with clearance.

  • OUYANG Huimin ZHANG Guangming MEI Lei DENG Xin
    . 2014, 33(23): 165-172.
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    Rotary cranes are widely used to transport heavy loads and hazardous materials in various environments, such as shipyards, factories, nuclear installations, and construction sites. Because horizontal motion of booms in rotary cranes typically generates undesirable two dimensional load sway, a trajectory generation method is proposed for achieving boom positioning and residual load sway suppression. Firstly, a partial linearized dynamic model of a rotary crane that includes a centrifugal force term responsible for two dimensional load sway is derived. Next, an S-shaped curve trajectory that can suppress residual load sway is generated by numerical calculation. The parameters of the trajectory can be obtained only by solving algebraic equations. This trajectory may be applied to conventional industrial controllers for reducing their system construction cost. Finally, comparative simulations and experimental results demonstrate the effectiveness of the proposed method. Therefore, the crane can be precisely operated without sensor systems for measuring load sway, consequently, the structure of the crane can be simplified and implementation cost can be reduced.

  • Xiao Tongliang;Qiu Hongxing;Tao Xin;Sun Jian;Chen Chunchao
    . 2014, 33(23): 173-178.
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    Steel-fiber-reinforced polymer composite bar (SFCB) is a new kind of reinforcing material. It has some excellent properties such as corrosion resistance and stable post-yield stiffness. This paper focuses on the nonlinear seismic response analysis of the steel-basalt fiber composite bars concrete frame, including deducing the flexibility matrix of frame element based on the Gauss-Radau integral method, which is used for nonlinear time history response analysis of the frame structure. A RC frame and a corresponding SFCB concrete frame were designed in the district against 8 degree earthquake according to the current Code for Design of Concrete Structures. The seismic performances were compared, including rates of natural vibration period, nonlinear time history response, when and where the plastic hinge emerged. The results show that the SFCB frame has less interlayer displacement angle and maximum elasto-plastic displacement than the RC frame under the frequent and rare earthquake ground motions. Under the rare earthquake ground motion, the SFCB frame has a smaller rate of natural vibration period than the RC frame, with even slighter stiffness degradation and damage degree. Furthermore, fewer plastic hinges appear at the ends of the members in the SFCB frame and at a relatively later time, which is more likely to form the beam-hinge plastic energy dissipation mechanism. the steel-basalt fiber composite bars can make full use of the strength of materials by rational allocation of steel bar and basalt fiber, it can effectively control the plastic deformation and decrease the residual displacement of frame structure, and thus reduce the gravity second-order effect on columns and improve the seismic performance of the whole structure.
  • Zhai peng Wang meng Xiao Jiahai Zhang Hongyang
    . 2014, 33(23): 179-183.
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    The motional analysis to beam impact during the mold opening and closing of mechanical vulcanizers was presented.The continuous accelaration main guide curve was presented. The mathematical model was build up and the simulation and optimal design based on CATIA was presented. Finally the processing code to the determined optimal guide curve was produced by CATIA_CAM, and the guide of vulcanizer wall board was produced to implemented on the vulcanizer overhaul. The beam impact was reduced by 77% so that the vulcanizer impact was resolved. The method was used in 3 vulcanizers overhaul by vulcanizer company and have got good effect.
  • Li Xue-hong Li Ye-xuan Wu Di Xu Xiu-li Li Zhi-jun
    . 2014, 33(23): 184-189.
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    Many ground motion intensity indexes were used to the structure seismic analysis, but there were no unified final conclusion and lack of systematically analysis on the applicability for these index. The correlation between the ground motion intensity and the structure seismic response was investigated by inputting 100 typical ground motion records to the SDOF system and the seismic-isolation-and-reduction continuous-beam bridge which have different period. The results show that the intensity index can be separated into four groups. The group I index represented by Sa(T1) has a high correlation with different period structure. The group II index represented by PGA has a high correlation with short period structure. The group III index represented by PGD has a high correlation with middle period structure. The group IV index represented by PGV has a stable correlation. The group I index is suggested to used as the ground motion intensity. A practical engineering analysis shows that different intensity indexes have different correlation with the known natural vibration period structure.

  • Chen Jiang;Xiong Feng;
    . 2014, 33(23): 190-194.
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    The gas-liquid-solid tri-phase coupling numerical model of the air-cushion isolation control was presented in this paper, in which the cracking behavior of concrete was considered. The radiation damping effect on truncated boundary of dam foundation was considered by using viscous-spring artificial boundary condition. The 3D nonlinearity simulation of air-cushion isolation effects in concrete gravity dam was carried out for the first time. It shows that air-cushion reduces the hydrodynamic pressure and acceleration effectively, so the cracking range of dam body are decreased. As the thickness of air-cushion increases, the reduction of hydrodynamic pressure and acceleration increases, the increment rate of reduction degree decreases progressively. Compared with uniform-thickness air-cushion, variable-thickness air-cushion can improve the utilization ratio and develop the air-cushion isolation effects more effectively. In the various cases of this paper, the maximum of hydrodynamic pressure is reduced by 50% approximately, the maximum of dam crest acceleration is reduced by more than 30% with variable-thickness air-cushion.
  • SUN Zhang-dong ZHU Cai-chao LIU Huai-ju LIU Ming-yong GU Zong-lin
    . 2014, 33(23): 195-199.
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    Numerical analysis of grease elastohydrodynamic Lubrication for Cycloid Drive, calculate the minimum film thickness value of meshing process and Compared with the experience formula, verify the mathematical model correctness. The average radius of cycloid gear lubrication state as the judgment basis, the effects of rotational speeds,load and rheological parameter on EHL of grease were analyzed. Results show that as speed goes up, the greater the film thickness and pressure spike, and the pressure spike moves toward inlet; As load goes up ,the contact width increase and the pressure spike moves toward outlet, the film thickness decrease less evident; As rheological parameter goes up , the greater the film thickness and pressure spike, and the pressure spike moves toward outlet. Discusses the effect of short amplitude coefficient for lubrication, as short amplitude coefficient decrease, the lubrication performance are improvement.
  • ZHOU Xiang-xin;WANG Xiao-min;YANG Yang;GUO Jin;WANG Ping
    . 2014, 33(23): 200-206.
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    Turnout vibration signals are important information in the high-speed turnout damage monitoring. As the signals are interfered with strong noise during the process of field acquisition and transmission, the accuracy of damage identification based on noisy vibration signals is declined seriously. To overcome this problem, a denoising method is generally employed before the damage identification. The complex and noisy vibration samples from the field, however, raise the hurdle for denoising. An effective denoising method based on wavelet threshold for turnout vibration signals is proposed in this paper. The wavelet basis, decomposition scale, threshold criteria and threshold function are empirically discussed for wavelet threshold denoising. Then damage identification analysis is conducted by the principal component analysis (PCA) of frequency response function (FRF) and average Mahalanobis distance (MD). The experimental results show that the method can reduce the noise interference effectively for damage identification, and create favorable conditions for further damage analysis.