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Table of Content

    10 November 2014, Volume 25 Issue 21
    Fourier Series Method for Motion Generation of RCCC Mechanism
    2014, 25(21):  2841-2847. 
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    Based on the Fourier series theory, the geometrical model of the rigid body rotation angle of RCCC mechanism was established. Two numerical atlas databases which contained 91 125 groups of basic rotation angle dimensional types and 562 500 groups of basic dimensional types of RCCC mechanism were built up by harmonic analysis. Subsequently, the formulas which could compute the real size and installing dimensions of the RCCC mechanism were proposed. On the basis of the theoretical formulas and two numerical atlas databases, the problem of rigid body guided synthesis of RCCC was solved. Finally, an example was given to show the feasibility of this approach.

    Dynamics Modeling and Analysis on Vibration Characteristics of Roll Grinder with Pillow Looseness
    Ding Yan, Shao Yimin, Yuan Yilin, Wang Shengjun
    2014, 25(21):  2848-2852,2859. 
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    To study the effects of pillow looseness on dynamic behavior of a roll grinder, a dynamics model of the grinder was proposed based on the two time delays model. Then the dynamic responses of the grinding system were solved. Investigations on the vibration responses and the envelope spectrums of the grinding system with or without pillow looseness were carried out numerically and experimentally. A good agreement between the simulation results and experimental results validates the effectiveness and accuracy of the proposed model.

    Equivalent Acoustic Transfer Vector Method for Analysis of Sound Field in Irregular Enclosure
    Xiao Yue, Chen Jian, Jiang Fengxin
    2014, 25(21):  2853-2859. 
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    Equivalent acoustic transfer vector method for the analysis of sound field in irregular enclosure was developed. The sound field formed by the complex vibrating structure was replaced by the superposition of a series of virtual sources near the surface of the cavity, and the strength of those sources was obtained by matching the normal velocity on the surface. The connection between the normal velocity on the surface and the sound pressure at the interested point in the cavity was established, and the calculation formula of panel acoustic contribution was deduced. Compared with boundary element method, complicated numerical calculation and the singular integrals were avoided in the proposed method, and the calculation efficiency was improved. The simulation results show that the proposed method is correct and effective.

    Forming Process of Bearing Materials Suitable for High-speed Bearings
    Jia Qian, Li Yuezong, Chen Runlin, Xi Yanhui, Dong Guangneng, Yuan Xia
    2014, 25(21):  2860-2864. 
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    Aiming at the problem that low temperature resistance and low mechanical properties of the bearing Babbit under high-speed conditions, a new process was designed by the axiomatic design method. The new process improves the deficiencies of the original process by adding a small amount of Cu and controlling cooling rate. Through the mechanics of materials and the friction and wear experiments, material performance of Babbitt which was manufactured in new craft was validated. Compared with the original process, temperature performance, resistance to compression properties get enhanced and tribological performance has been improved,when Babbitt was manufactured in new crafts. High-speed bearing test rig preliminary assessment tests show that:tested bearing runs smoothly,the indicators meet the requirements.

    Failure Simulation Analysis and Eexperimental Verification of Bearings for Spaceborne Moving Mechanism
    Liu Tingwei, Zhang Ning, Liang Wei, Zhang Liang
    2014, 25(21):  2864-2868. 
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    To evaluate the life of solid lubricated bearings of rotation mechanism on the long life satellite, a physical quantitative model of the bearing failure mode was researched firstly combining with the theory of Hertz contact theory. Secondly, from the aspect of bearing dynamics,actual working conditions of the bearings which were installed on the single load were simulated through the computer simulation method, and the bearing contact friction properties and mechanical properties rule were gained. Finally, simulation results were verified with several measurable physical quantities through actual tests and then closed loop verification goal was achieved. Research results validate that the solid lubricated bearing dynamics modeling method is correct, and provide internal lubrication failure of low speed solid lubrication bearing with the quantitative criteria, and ultimately provide a method of improving the long life of two-dimensional scanning mechanism.

    Research on Potential Energy Recovery System for Electric Forklift
    Zhang Kejun, Chen Jian
    2014, 25(21):  2869-2874. 
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    In order to save energy, a potential energy recovery system for electric forklift was proposed based on generator and super-capacitor. Control strategy of potential energy recovery system was given, parameters of the system were analyzed and designed. AMESim and MATLAB were used to analyse potential energy recovery efficiency, then through experimental study the effectiveness of simulation model and the accuracy of simulation results were tested. The simulation and experimental results show that the parameters of potential energy recovery system are reasonably matched, energy recovery effect is obvious.

    Importance Measure of Revolute Joint Clearance about Motion Accuracy of Linkage Mechanism
    Sun Zhongchao, Yu Tianxiang, Cui Weimin, Song Bifeng
    2014, 25(21):  2874-2879. 
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    In order to study the contribution of the joint clearance uncertainty on the output error uncertainty of mechanism, a gear door mechanism of an airplane was taken as example to illustrate the IM of the revolute joint clearance. Firstly, the kinematic model of the mechanism was constructed. Secondly, the components of the mechanism were classified as two-force bars and bending parts. Based on the “equivalent length theory”, the motion accuracy model and reliability model of the gear door mechanism were constructed. At last, with the moment-independent IM method about motion accuracy and failure probability, the IM of joint clearance was emulated under different distribution parameters. From the emulation results one can get that the variance has a bigger affection on the importance value of the joint clearance than that of mean value.

    Gear Fault Feature Extraction Method Based on Adaptive MCKD and FSWT
    Zhong Xianyou, Zhao Chunhua, Tian Hongliang, Chen Baojia, Zhao Meiyun
    2014, 25(21):  2880-2885. 
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    Aiming at the problem that denoising effect of the MCKD was subject to order of the filter,a adaptive MCKD method was proposed,aiming at the deficiency of FSWT extracting impulse fault features from strong noise background,a fault feature extraction method for gears was proposed based on adaptive MCKD method and FSWT. Firstly,by using adaptive MCKD,the noise in the gear vibration signals was reduced,then the denoised signals were decomposed by applying FSWT to extract fault characteristics,gear fault vibration signals analysis demonstrates the effectiveness of the method.

    Time Determination and Life Assessment of High-speed Railway Bearing Reliability Test
    Zhu Dexin, Liu Hongzhao, Yuan Daning, Wang Lei, Liu Lilan
    2014, 25(21):  2886-2891. 
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    For the limit of cost and time, the high-speed railway bearings reliability test adopted the program of fixed time and small sample test usually. In this case, how to determine the test time and evaluate the reliability of these no-failure bearings were the important problems which needed to be studied further. Herein, starting from the fatigue life distribution of high-speed railway bearing, the mathematical models of sample size and test time were deduced. And the hierarchical Bayesian estimation was used to process the zero failure test data, then the high-speed railway bearing reliability life evaluation model was established. Taking domestic high-speed railway bearing as an example, the simulation results were given.

    Geometric Error Modeling and Analysis for CNC Gear Hobbing Machine
    Han Jiang, Xia Haisheng, Xia Lian
    2014, 25(21):  2891-2895. 
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    The structure of CNC gear hobbing machine was analysed based on the theory of multi-body system, the topological structure for CNC gear hobbing machine was acquired; the movement  relationship between adjacent body was researched, the geometric error model of CNC gear hobbing machine was gained according to the movement relation between adjacent body and the topological structure for CNC gear hobbing machine. By decoupling the geometric error model , the compensation quantities of separate axis are obtained, which is laid a theoretical foundation for CNC gear hobbing machine geometric error compensation.

    Design and Dynamics Simulation of Logarithmic Spiral Surface Wedge Block Backstop
    Li Haiquan, Fu Lihua, Ma Beiyi, Li Gang, Yu Chengzhong, Song Hua
    2014, 25(21):  2896-2901. 
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    Through designing logarithmic spiral surface wedge block that was the core part of backstop, a new backstop with logarithmic spiral surface wedge block was pointed out. This paper used the Pro/ENGINEER software to establish the three-dimensional model of the backstop. Then, the model was imported into ANSYS/LS-DYNA software for dynamics simulation analysis to obtain the stress characteristics during the backstop process.This study will offer theoretical basis for the production of the new backstop.

    Energy Partition to Workpiece in Grinding GH4169 Superalloy with Single Alundum Wheels
    Wang Tao, Chen Guoding, Zhang Chaoyang
    2014, 25(21):  2901-2906. 
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    The necessity of determining the energy partition to workpiece in grinding process for the mechanism of grinding GH4169 superalloy was presented. But the existing equations had limitations when they were used to determine the energy partition in grinding GH4169 superalloy process. A method that combined experiment with FEM for determining energy partition was proposed, and the energy partition to workpiece in grinding GH4169 superalloy process with single alundum wheels was determined. The correlation between energy partition and grinding process parameters was analysed and described by an empirical equation. The results indicate that the energy partition to workpiece under the process conditions of this work ranges from 25% to 62%,and that the relationship between the energy partition to workpiece and grinding process parameters can be expressed by a exponential function equation.

    Research on Five-Axis CNC Machining Method of S Shaped Detection Test Piece
    Du Li, Zhang Xin, Zhao Shuangyu, Li Junjie
    2014, 25(21):  2907-2911. 
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    As a new member of international standard specimens, “S” shape detection test piece became a problem in the processing area due to its complex shape. In the environment of UG NX, through some operations such as three-dimensional modeling, process planning, CNC programming, “S” piece post processing commands were derived. Based on virtual machine tool theory, a machining simulation universal platform was set up, and the accuracy of processing program was verified. A variety of methods of five-axis CNC programming were adopted, and theoretical errors of various programming methods were compared through the  simulation platform. The post commands with minimum theoretical errors were selected to cutting experiments, they realized five-axis machining of “S” piece.

    Intelligent Fault Diagnosis for Rotor Using MSHOSSE and GA-VPMCD Method
    Luo Songrong, Cheng Junsheng, Yang Yu
    2014, 25(21):  2912-2917,2924. 
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    Firstly, according to nongaussian and nonlinear characteristics of rotor fault vibration signals, combining higher order statistics analysis,singular spectrum analysis, information entropy and multi-scale analysis, a conception of MSHOSSE was presented and applied to rotor fault feature extraction. Secondly, VPMCD was a new class discriminate approach, which was of excellent learning ability for small samples and multi_classification, however, the choice of model type existed subjectivity. Thus, an improved class discriminate method based on GA and VPMCD (GA_VPMCD) was presented in the course of rotor fault diagnosis using VPMCD by the global optimization performance of genetic algorithm (GA) and fusion diagnosis method. Finally, a novel intelligent fault diagnosis method based on MSHOSSE and GA_VPMCD was put forward. Simultaneously, the method was applied for rotor fault diagnosis. The experimental results show its effectiveness and superiority.

    A Tool Path Pre-compensation Method for 3-axis Machining Using Contour Error Model
    Li Xuewei, Zhao Wanhua, Lu Bingheng
    2014, 25(21):  2918-2924. 
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    To reduce the contour errors in multi-axis machining caused by the dynamic characteristics of feed system, a new path pre-compensation method was proposed. In the new method, a contour error model was built to calculate the compensation vector by reading the interpolation data of the CNC system in real time. Simulations and experiments were carried out for the compensation of circle, variable curvature trajectory and helix machining. The results indicate that the new method proposed herein can compensate more than 85% contour errors caused by the dynamic characteristics of the feeding system in 2-axis and 3-axis machining and the accuracy of multi-axis machining of the machine tool is improved significantly.

    Experimental Study of Shock Load Characteristics of Stranded Wires Helical Springs
    Wang Shilong, Tian Bo, Zhou Jie, Zhao Yu, Cheng Cheng
    2014, 25(21):  2925-2929. 
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    In the case of stranded wires helical springs used for the recoil spring, the shock response dynamics model of stranded wires helical springs and each spring coil were established in accordance with the mass-spring-damper model. Through the experiments of shock load, the internal motion regularity of the spring was analyzed, and the modal parameters such as the equivalent stiffness and the equivalent damping were identified. The results indicate that the structure of stranded wires helical springs is nonlinear under the shock load, which can reflect more advantages of damping. The internal motion regularity of the spring is nonlinear either, and the speed of spring coil along the axial direction is no longer a linear distribution.

    LRPSO Algorithm and Applications in Reliability Optimization
    Chen Dongning, Yao Chengyu, Wang Bin, Zhang Ruixing,
    2014, 25(21):  2930-2936. 
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    Fault probability function constructed by Bayesian network was regarded as reliability index, and the resource constraint functions were established by considering the functions of cost, weight and volume. To overcome the shortages of attraction and repulsion rule of particle swarm optimization algorithm, a LRPSO algorithm was proposed. At the earlier-stage, each particle searched the optimum under the attraction and repulsion produced by all particles, to maintain the population diversity. At the later-stage, the effect of attraction was reduced and the effect of repulsion was enhanced using the repulsion term to avoid particles being trapped in worse searching position and improving local searching ability. The effectiveness of LRPSO algorithm was verified by algorithm tests and reliability optimization examples.

    Simulation of Pneumatic Driven Microdroplet Jetting Process and Experimental Study of Microdroplet's Uniformity
    Xiao Yuan, Huang Yachao
    2014, 25(21):  2936-2941. 
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    In order to achieve uniform droplets and stable jetting process by pneumatic DOD droplet generator, two-dimensional axisymmetric model was built to simulate the micro jet process by FLUENT. The forming process of the droplet generation and the influences of different cavity pressure peak on the single droplet formation were researched. The injection experiment  was conducted using developed generator to inject the water, and the uniformity of the droplet were studied. The simulation results show that the DOD whole stable forming process of droplet is obtained and low pressure pulse peak in the cavity is beneficial to improve the ejection stability of the droplets. The experiments show that the attached diameter of droplet maximum change rate is 1.82% and the droplet has a good uniformity.

    Rotating Machinery Fault Diagnosis Based on Local Mean Decomposition and Hidden Markov Model
    Meng Zong, Yan Xiaoli, Wang Yachao
    2014, 25(21):  2942-2946,2951. 
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    Based on LMD and HMM, a new method for rotating machinery fault diagnosis was proposed. The method was applied to rolling bearing fault diagnosis. First of all, fault signals were decomposed by LMD, the instantaneous energy distribution of each signal was extracted to form the fault feature vectors, and then input the feature vectors into the HMM classifier for malfunction recognition, the maximum likelihood probability which was output by HMM classifier was in the fault state. A practical fault signal of a rolling bearing with corrosive pitting was applied to test the method. Experimental results show that the method of LMD-HMM is superior to the method of empirical mode decomposition(EMD)-HMM and can identify the rolling bearing faults accurately and effectively.

    Optimal Compound Straightening Rules Based on Heavy Rail of Uniform Test
    Song Hua, Lian Fabo, Li Kuixing, Tong Shanhu, Jia Hao, Yuan Siyu, Wang Zhongqian
    2014, 25(21):  2947-2951. 
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    This paper used uniform test to design compound straightening rules, ANSYS/LS-DYNA explicit dynamics software was applied to simulate the rail compound straightening process, taking the residual stress and flatness that were after the rail straightening as an indicator to carry on statistical analysis. Then the optimal compound straightening rules, as well as the adjusting function and effects of every straightening roll were obtained.

    Error Compensation of Aspheric CNC Machining by Tangent Method
    Yu Bo, Yu Zhenglin, Gu Lidong, Zhou Jiahe, Hu Yue
    2014, 25(21):  2951-2954,2961. 
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    The paper contraposed tangent method principle of aspheric CNC machining speed interpolation, an error predictive compensation method was proposed, that was based on the HMM theory, combining threshold constraint technology and expectation evaluation ideas of statistics. According to the method,the paper established “aspheric CNC machining by tangent method” error compensation model. Through the practical applications and the experimental analysis the error predictive compensation method can solve the error's problem of CNC machining effectively, the method can be applied to interpolation principle of the control system, and applied other interpolation principles. The error predictive  compensation method proposed is a new attempt in the field of error compensation research, in the long run, it will have good prospects for development and a more broad space for applications.

    Research on Tolerance Optimization Allocation Method Based on 3D Drawings
    Ai Yandi, Liu Zijian, Yu Zhimin
    2014, 25(21):  2955-2961. 
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    Using MBD and dynamic isolog tree data framework an implementation method of 3D drawings was proposed to provide quality data sources for the tolerance optimization allocation process of NC machine tool. A tolerance analysis model was constructed based on the Jacobi spinor method, and sensitivity analysis for each link of tolerance chain was carried out. Under the conditions of the design requirements and with the principles of minimum cost, the optimal allocation of tolerance in each link was obtained. With grinding head of gantry rail grinder as example, 3D drawings of its components were set up, and the tolerance optimization allocation was completed in the system. The feasibility of tolerance optimization allocation method based on 3D drawings was verified.

    Measurement Method of Invalid Injection Time for a Low Pressure Electronic Gasoline Injector
    Ye Chang;Zhang Zhendong;Cheng Qiang
    2014, 25(21):  2962-2967. 
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    Based on the structure model of a low pressure electronic gasoline injector, the motion law of the armature assembly and the changing course of the coil current within an injection pulse were analyzed combining with electromagnetic theory, and the consistency between the time of the armature assembly movement characteristic curve point appearing and the time of the coil current curve point mutating was confirmed. A new measurement method of invalid injection time for an electronic gasoline injector was found, and a measurement system was developed by using MCU technology. The comparative results show that: relative error of the measurement results is less than 2.94%, and absolute error is less than 0.02ms. The measurement method is effective and the measurement results are accurate.

    Design and Performance Simulation of Variable Volume HCU
    Zhao Zhiguo, Wu Xiaowei
    2014, 25(21):  2968-2974. 
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    The frequency of high-speed solenoid valve of circulating HCU affected brake experience. In order to solve this problem, this paper presented a variable volume HCU based on ABS-VI. Vehicle dynamics model was set up in MATLAB/Simulink, simultaneously the HCU model was set up in AMESim. And then the regulator performance and ABS function were co-simulated. Simulation results show that: this HCU has a wide range of brake pressure, and the wheel cylinder pressure can exceed the master cylinder pressure; the HCU and logic threshold control strategy can achieve ABS function; the voltage threshold value of regulator motor has effects on ABS performance.

    Analysis and Optimization of Coupled Vibration System for Vehicle Based on State Space
    Zhang Junhong, Wang Kainan, Bi Fengrong, Guo Peng, He Zhenpeng
    2014, 25(21):  2975-2981. 
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    This paper presented a study of a mechanics model of coupled vibration system with elastic supports based on state space theory, with subsystem coupling coefficient and relative attenuate coefficient to evaluate the transfer characteristics. Parameter study was taken using Latin hypercube sampling, and relationships among mount parameters and system coupling characteristics was discussed. Non-dominated sorting genetic algorithm was adopted to solve the multi-objective optimization problem and optimal solution set was obtained for vehicle coupling system, which was validated by transfer functions of subsystems. The results show that improvements of coupling characteristics of both engine/chassis and body/chassis subsystems in engine-chassis-body system can help optimize ride comfort quality of vehicles, and the method of optimization calculation to minimize relative attenuate coefficients is feasible.