Table of Content

10 January 2015, Volume 26 Issue 1

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Three Dimensional Linear PML Absorbing Boundary Conditions with an Oblique Mean Flow

Wu Xin, Chen Zhifu, Yin Hanfeng

2015, 26(1):  1-7. 

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For three dimensional linear Euler equations in the case of oblique mean flow, the dispersion relations of acoustic, vortex and entropy wave were first analyzed by using Fourier and Laplace transform method. Then the hypothesis for changed frequency was employed, a proper space-time transformation was presented for deriving three dimensional linear Euler equations in transformed coordinates. A complex change was applied to the new equations and a damping parameter was introduced. A three linear PML absorbing boundary conditions in the case of oblique mean flow for x layer, y layer, z layer and corner layer were derived. In addition, the importance of added absorption term was emphasized. Finally, the effectiveness of linear PML absorbing boundary conditions was validated by computing the computational aeroacoustics benchmark problems. The results prove that: the presented space-time transformation can solve the problem of direction inconsistence in group and phase velocity of physical wave; in the case of oblique mean flow, the proposed PML absorbing boundary conditions can absorb the physical wave with little or no reflection.Therefore,it also can be applied to aeroacoustic computation.

Theoretical Calculation and Experimental Analyses of Natural Frequency for High Frequency Dynamometer

Huang Zhen, Zhao Wei

2015, 26(1):  7-11. 

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Concerning the low natural frequency of dynamometers for high speed cutting to acquire forces signals, a initial model of high frequency dynamometer was designed and  its natural frequency can be as 9kHz. Based on the method of Dunkerley, a simplified model of the dynamometer was built to achieve the theoretical natural frequency and the computational formula. Meanwhile, the simulation values and actual values of the natural frequency were obtained by modal analysis with the use of the finite element simulation and vibration modal test, and the high speed cutting test was conducted for the validation. The results indicate that theoretical values and simulation values are a little greater than the actual values, and the dimensions of key structure have an great impact on the natural frequency, which provide a necessary reference for the structure optimization of similar dynamometers.

Free Vibration of Oscillating Tooth Drive for an Electromechanical Integrated Harmonic Piezodrive System

Li Chong, Xu Lizhong, Xing Jichun

2015, 26(1):  12-17,24. 

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An electromechanical integrated harmonic piezodrive system was proposed, which had the characteristics of low speed and high torque. The system output torque through oscillating teeth. The principles of the electromechanical integrated harmonic piezodrive system were discussed, the dynamic models and dynamic equations were set up. Frequency equations of free vibration of oscillating tooth were given and the natural frequencies and vibration modes were solved, and the impacts of parameters on natural frequencies were analyzed. These results provide basis for the improvement and the further research of the electromechanical integrated harmonic piezodrive system.

Optimization BUCK Model Used in Elliptic Ultrasonic Power Cutting Driving Device

Chen Mingfang, Zou Ping, He Yu, Wu Hao, Zhang Yongxia

2015, 26(1):  18-24. 

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Based on elliptic ultrasonic power cutting driving device of the BUCK converter model optimization research, fully considering the influence of each component parasitic parameters on the model, at the same time the LC optimization design was carried on the thorough analysis, an optimized converter model was designed and the appropriate verification circuit was made. Through analyses of two important BODE diagrams of transfer function model test of the model and simulation analysis, the results prove that the model better reflects the dynamic performance of the real circuit, better guides the design of the converter.

Leader-follower Joint Design of Product Family Based on Module Attribute Combination

Chen Mo, Du Gang, Zhi Huawei

2015, 26(1):  25-31. 

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Optional modules were always enacted within mandatory modules, and meanwhile an optimal mandatory modules configuration depended on how optional modules were to be chosen. For solving how to design two types of modules in different level, a bilevel mixed 0-1 nonlinear programming model was developed, comprising an upper-level optimization problem and a lower-level optimization problem. The upper level seeks for maximizing the shared surplus and commonality index of an entire product family. The lower level seeks for maximizing the utility of optional attributes. At last, through the case of bicycle product family, the feasibility and effectiveness of the model were validated.

Optimization Design for Multi-linkage of High-speed Mechanical Press

Li Yejian, Sun Yu, Hu Fengfeng

2015, 26(1):  31-36. 

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In order to exert the ability of press, and solve a series of problems of high-speed mechanical press, an compound optimal mathematic model about geometric parameters of main driving organization of high-speed mechanical press was established, which took minimum of crack and maximum of punching angle as the evaluation index. In the meantime, the optimal model was established with MATLAB. The optimization results show that the punching angle of organization is increased by 13.5%, and acceleration of main slider is decreased by 35.3%. The displacement curve is smooth in the near of bottom dead center. It is beneficial to a bundant deformation of materials in the process of stamping, the design of dynamic balance, and to improve the dynamic precision of the bottom dead center.

Structural Parameter Optimization of a Crossbar Parallel Machine Tool

Fang Xifeng, Zhang Sichong, Xu Qinhuan, Wang Tongyue, Liu Yuanwei, Chen Xiaogang

2015, 26(1):  37-43. 

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Increasing workspace and improving dexterity are important taskes for the design of parallel machine tool. On the basis of inverse kinematics, workspace of the crossbar parallel machine tool with constraints was obtained via three-dimensional search method. New Jacobian matrix of the machine was also deduced by using the natural coordinate method. Dexterity distribution of the machine was acquired as well based on the workspace and new Jacobian matrix. Then, the impacts of structural parameters on workspace and global dexterity index were analyzed, then least square method was applied to curve fitting and the optimization of these structural parameters were carried out by introducing workspace value index and global dexterity index as the global optimization goals. Compared with the original data, each of them increases by 0.40 and 0.26 times respectively, achieving the aim of mechanism optimization.

Influence of Tool Vibration Feeding on ECM Process in Machining Micro Multi-grooves

Zhao Jianshe, Li Long, Wang Feng, Xiao Xiong

2015, 26(1):  44-48,78. 

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A vibration feeding device system with multi-adjustable parameters was developed to precisely control the vibration feeding movement. By analyzing the influence of vibration feeding movement on the removal of electrolytic products in machining gap and the stability of electrolyte flow field and based on the machining of micro multi-grooves on razor grille, a series of experiments were carried out to study the influence of the vibration feeding parameters on microscale groove group's average width and sidewall taper. Finally, multi-grooves with width 0.26mm and sidewall taper less than 5% were batch processed with the optimum parameters. The experiments have proved that vibration feeding can effectively improve the machining accuracy and the machining process stability on ECM process in machining micro multi-grooves.

A Stigmergy-based Holonic Control Architecture and Scheduling Strategy

Tang Hongtao, Liu Lu, Chen Ming, Lu Jiansha

2015, 26(1):  49-54,62. 

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Aiming at the hierarchical control architecture of manufacturing execution system and the application limitations of Stigmergy in Holonic control architecture, a Stigmergy-based Holonic control architecture was proposed by introducing an ant holon for every basic holon and staff holon.Four internal holons (data holon,decision holon,communication holon and structure holon) were designed for each holon unit.According to different application scopes two types of pheromones were defined. Aiming at the optimization objective of total completion time,a basic Job Shop scheduling strategy achieved by each holon unit under the Stigmergy-based Holonic control architecture was proposed. The validity of the method was verified through an example calculation.

Online Tolerance Optimization for Remanufactured Complex Mechanical Product Assembly Processes

Liu Mingzhou, Xing Lingling, Liu Conghu, Zhang Miao

2015, 26(1):  55-62. 

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To improve the assembly precision of remanufactured complex mechanical products and the utilization ratio of remanufactured parts, an online tolerance optimization approach for remanufactured complex mechanical product assembly processes was put forward. First, the tolerance zone of the key process was divided into several zones with fine granularity based on the analysis of remanufactured complex mechanical product assembly characteristics. Second, under dimensional chain constraints, based on genetic algorithm an online tolerance optimization model was established with the minimum quality loss and comprehensive cost as target. Then a forward inference mode based on historical data and an backward inference mode based on the real-time assemble information were proposed respectively, which can dynamically deduce the optimal assembly scheme set guiding the remanufacturing assembly process and timely response to the abnormal. Finally, an online quality control prototype system for the remanufactured engine assembly in a power corporation remanufacturing assembly line was developed, which shows the feasibility and validity of the proposed strategy.

Fault Diagnosis of Rolling Bearings Based on Morphological Difference Filter and Difference Entropy

Jiang Wanlu, Zheng Zhi, Zhu Yong, Li Yang,

2015, 26(1):  63-70. 

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Concerning the early fault diagnosis of inner and outer race, a novel method was proposed. The method put the advantages of mathematical morphology filtering nonlinear signals and the advantages of information entropy theory characterizing signals together. Firstly, the measured slight and severe fault signals of inner and outer race faults were filtered by morphological difference filter to get more useful fault characteristic informations. Secondly, the abrupt informations of signals were extracted by difference entropy, and the uncertainty and complexity of abrupt information were measured by difference entropy. Lastly, the faults were diagnosed successfully based on the mind of the periodic time interval of abrupt point coincided with the periodic impulsive time interval of inner and outer race faults. The simulation signals and the two fault signals of the rolling bearing were tested and verified, the result is that the new method can diagnosis the early faults of inner and outer race with high accuracy.

Method for Automatic Generation of Exploded View Based on Synchronous Constraint Release

Zhao Hongfei, Zhang Qi, Wang Haitao, Zhao Yang, Fang Baoshan

2015, 26(1):  70-73. 

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To improve learning of structure design and training maintenance persons, a method for generating exploded view automatically was proposed based on synchronism release of parts geometric constraint relations. Part adjacency restriction relation matrix and restriction type matrix were built by defining part disassembly axial. Parts were stratifed according to the sequence of geometric constraint synchronism release, and sub-assembly was identified by defining rules. A method for parts isometric rate explosive separation form outside to inside was constructed. OBB(oriented bounding box) and FDH(fixed directions hulls) bounding boxes were used to realize the automatic generation of assembly component parts exploded view.

Rotor Fault Diagnosis Methods Based on Local Tangent Space Alignment and K-Nearest Neighbor

Sun Bin, Liu Liyuan, Niu Chong

2015, 26(1):  74-78. 

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In order to solve the problem that the large mechanical equipment failure data is difficult to accurately extract, this paper put forward a kind of rotor fault diagnosis models based on LTSA and KNN. The vibration signals of rotor structure were used to construct dimensional matrix, then the low dimensional feature vector of high dimension matrix in the LTSA was extracted,and projected into the visual space.And the extracted low dimensional feature vectors were put into the KNN in order to do fault pattern recognition. Finally, experimental and data dimension reduction simulation process shows that the accuracy and rapidity of the method with LTSA and KNN are better than the fault diagnosis model by neural network and support vector machine.

Identification and Optimization of Linear Servo System Controller Parameters Based on Iterative Learning of Orthogonal Projection

Yang Liangliang, Shi Weimin, Liu Yisheng, Zhou Yunfei

2015, 26(1):  79-85. 

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According to the problem of feedforword parameter identification in linear servo system with high frequency response, a method of orthogonal projection was introduced. At first, orthogonalized basis functions were constructed and the control system was projected onto the axes of the basis functions,then system parameters were identified along the axes of basis functions by iterative learning and high speed response were compensated by feedforword.The method extends the iterative learning from time domain to the space of orthogonalized basis functions. The simulation and experements show this method can improve the tracking and high-response performance of linear servo system significantly and meet the high speed and high precision requrements.

Prediction on Machining Accuracy of Five-axis Milling Tool for Multiple Error Source Coupling

Wang Wei, Zheng Congzhi, Zhang Xin

2015, 26(1):  85-91. 

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 A method integrated with dynamic error factors and static geometric errors was presented to build the surface data of actual workpiece. Each servo axis movement was simulated and composed by kinematics of the joint bodies of the machine for calculating the actual position and attitude of the tool. The actual milling point was solved by the envelope theory and the final part of the surface was obtained by the surface forming method. A case study was analyzed through the S specimen sample, which was verified the composition of surface methods and get the milling errors caused by influences of dynamic factors, such as the gap, the position loop and speed loop. The results were verified by experimental data through regression analysis. Finally, the error track model was established based on neural network for condition assesment after machining. The developed platform may provide technical support for the realization on precision forecasting and security for large-scale and the key structure.

Experimental Research on High-temperature Diffusion Annealing Process of Steam Turbine Rotor Forgings

Liu Xingang, Chen Huan, Jin Miao, Wang Yuhui, Zhang Qinghua

2015, 26(1):  92-97. 

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Based on experiments, combined with the practical production of high pressure steam turbine rotor forgings, the variation of grain size, microstructure and mechanical properties in different holding times and forging fire times were studied, the influences of high-temperature diffusion annealing on 30Cr1Mo1V steel were revealed as well. The results show that the banded structure produced by dendritic segregation and forging deformation can be eliminated by high-temperature diffusion annealing. The grain size is smaller only before forging high-temperature diffusion annealing. The transverse toughness of the 30Cr1Mo1V steel can also be improved by homogenization. The grain and the structure are coarsened because of long time high temperature heating after forging, which leads to the worse toughness of the steel. Meanwhile, the plasticity of 30Cr1Mo1V steel is not influenced by the high-temperature diffusion annealing obviously.

Structure Optimization for Main Body of Vertical Microstructure Profiler

Jiang Xin, Liu Yuhong, Song Shijun, Wang Yanhui

2015, 26(1):  97-101. 

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Vertical microstructure profiler (VMP) is a most common and effective platform to obtain data of microstructure turbulence in the ocean. The FIV is the main factor affecting the measurement precision of the VMP. Factors influencing the FIV of the VMP were analyzed herein. Based on the numerical simulation platform of ANSYS-Workbench, the FIV of the VMP with various shapes and structure parameters was calculated using algorithm of two-way fluid-structure coupling. Aimed to decrease the FIV, the main body shape and the structure parameters of the main body were optimized respectively. The measurement precision of the optimized profiler is improved by 57%. The present investigation provides scientific guidance for designing the VMP.

Process Parameter Optimization Based on BP Neural Networks and GA in Point Grinding Low Expansion Glass

Ma Lianjie, Cao Xiaobing, Gong Yadong, ChenN Xiaohui

2015, 26(1):  102-106. 

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The trends of experimental data were analyzed, the surface roughness and surface hardness were tested in point-grinding low expansion glass ceramics. The numerical models of surface roughness and hardness were established by the least square fitting. The accuracy of the model was tested by coefficient of determination, and the model predictions were compared with experimental data to validate the accuracy of the model. The results indicated that the model has high accuracy. Based on BP neural networks and GA, the multivariate numerical models were built on surface roughness and hardness according to the results of orthogonal experiments. And both of the models were selected as the objective function. Optimization goal was the minimum of surface roughness and the maximum surface hardness, dual objectives optimization was carried out based on GA. A range of the optimal solution was obtained about point grinding process parameters. Experimental validation results indicate that optimal results are reasonable.

NURBS Curve Interpolation Algorithm Based on Recursive Feature Analysis

Han Jiang, Jiang Benchi, Xia Lian, Tian Xiaoqing

2015, 26(1):  107-111. 

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Based on the recursive feature analysis of the base function in NURBS formula, a novel interpolation algorithm was put forwards. The method obtained the next parameter increment by a previous parameter increment and a previous chord length, and then the parameter interpolation was achieved.Simulation results show that, the proposed interpolation algorithm has obvious advantages in improving chord length errors and lessening computation load compared with those using Taylor's equation.

Study on Microstructure and Tribological Properties of Y₂O₃ Modified Graphite/CaF₂/TiC/ Ni-base Alloy Composite Coatings

Cai Bin, Tan Yefa, Hu Xiaoguang, Tan Hua, Tang Jian

2015, 26(1):  112-119. 

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In order to improve the friction and wear properties, the graphite/CaF₂/TiC/Ni-base alloy(GCTN) composite coatings were modified Y₂O₃ and prepared by plasma spray on the surface of 45 carbon steel. The microstructure, microhardness, fracture toughness and tribological properties of the composite coatings were researched. The results show that the Y₂O₃ modified GCTN composite coatings are mainly composed of γ-Ni, CrB, Cr₇C₃, TiC, CaF₂ and graphite. Y₂O₃  reacts with C and produces active element Y by the heat of plasma flame. Y can purify the γ-Ni structure, refine the grain size of CrB and Cr₃C₇, and improve the density of the composite coating. When Y₂O₃  is 0.5wt%, the microhardness and fracture toughness of the composite coating are 593.3MPa and 6.82MPa·m^1/2 respectively, which are increased by 8% and 22% than those of the composite coating without Y₂O₃ , because of the refining strengthening effort of CrB and Cr₃C₇. The improvement of microhardness and fracture toughness of the GCTN-0.5Y₂O₃  composite coating reduces the adhesive wear and micro fracture wear, so it presents the lowest friction coefficient and wear rate, which are 0.085 and 0.39×10-3mm3/m respectively.

Flanging Process Synchronized Simulation for Automobile Panels Based on CATIA Platform

Ding Tianxu, Liu Yuqi, Zhang Zhibing, Yu Wen, Du Ting

2015, 26(1):  120-124. 

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FS(flanging simulation) system for automobile panels was developed based on the CATIA platform. This system introduced the idea of the mold structure travel diagram into FS, and took into account the flanging direction, drive angle and stroke's impact on flanging forming, which could truly reflect flanging movement relationships and effects of inserted cross-cutting on flanging. It made motion simulation by the way of animation, which could check interference of tool moving. It also achieved the CAD/CAE integration, which avoided losing model data and accuracy during the platform transformation.In the CATIA user-defined feature updating mechanism, this system can update CAD models and CAE models synchronously, which can save the CAE modeling time repeatedly during early stage of product design, improve the efficiency of the designers. Through analyzing specific case, the stability and accuracy was proved.

Optimization Design for Crashworthiness of Sub-frame Side Rails

Yang Jikuang, Hua Changxing, Xiao Zhi

2015, 26(1):  124-129. 

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In order to optimize design of a whole box-type sub-frame side rails in terms of structural parameters to meet the requirements for light weight and crashworthiness in front impact,an optimization mathematical model was established in terms of design variables of the sub frame side rails. First, analysis of variance was carried out to choose the factors that had significant influences on the light weight and crashworthiness of sub-frame side rails as the main design variables. Secondly, a design test was conducted by using orthogonal experimental design method. Then, the Ls-dyna program was utilized for crash simulations. A response surface approximation model was built up according to the simulation results, and the approximate model was validated to solve the reliability problem. The results show that the model established by the response surface is suitable for solving the combined optimization problem in this study. The optimized sub-frame side rails can improve crashworthiness performance while maintain a good light-weight level.

On-line Automatic Vehicle Driving Wandering Test System Based on Binocular Vision

Zhou Xinglin, Li Cheng, Liu Hanli, Jiang Nande, Zhang Yun, Hu Yiwei

2015, 26(1):  130-134. 

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 In order to solve the measurement problem of vehicle driving wandering, an on-line automatic vehicle driving wandering test system was developed. By setting up a binocular vision measurement model, the system realized automatic measurement of the vehicle driving wandering quantity. The self-developed wide field of the laser light source solved ambient interference problems when measuring. Data processing algorithm which was optimized solved the problem of lower measurement accuracy. The wireless network test system realized on-line automatic measurement of the vehicle driving wandering. This system has high detection accuracy; it runs stably and reliably. It can be widely used in automatic on-line measurement of vehicle driving wandering quantity in automobile manufacturer and all kinds of vehicle inspection.

Effects of Nonlinear Tire Lateral Force on Vehicle Steering Stability

Shen Fapeng, Zhao Youqun, Zhao Hongguang, Liu Yingjie

2015, 26(1):  135-139. 

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To analyze the effects of tire lateral force, a nonlinear model of tire lateral force was established and a 4-DOFs vehicle dynamics model was adopted to calculate the responses of vehicle side slip angle and roll angle and front wheel steering angle with different velocities. The results of virtual experiments based on ADAMS and real vehicle experiments demonstrate that the nonlinear tire model can more accurately reflect the response of vehicle movement states under the conditions of high-speed steering, and the mean absolute errors of each state response can be guaranteed within 10% of the corresponding state amplitude. The conclusions may provide theoretic direction for the design of vehicle stability control system.