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Table of Content

    10 April 2018, Volume 29 Issue 07
    High-performance Precision Manufacturing
    GUO Dongming
    2018, 29(07):  757-765. 
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    High-performance manufacturing is the integrated manufacture of function and geometry, which aims at the precise guarantee of key parts of high-end equipment and products. It indicates the great progresses from the conventional manufacture with requirements of geometrical dimensioning and tolerancing to the advanced manufacture with primary requirements of high performance. From the points of view of the current status, requirements and development trend of manufacture,the features, facing challenges and its classification of high-performance manufacturing, as well as the connotations of high-performance parts, were analyzed and explained in depth combined with application examples. It provides a feasible route and solution strategy for the precise manufacture of a large number of key parts in high-end equipments.
    Applications of Advanced PSO-Elman in Engine Crankshaft Pulse Width Predictions
    MENG Rongge1,2;ZHANG Chunhua1;LIANG Jichao1
    2018, 29(07):  766-770. 
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    Aimed at the unpredictability of the engine crankshaft pulse widths, advanced PSO-Elman predictive method was put forward. The model of pulse width predictions was built by Elman neural network, according to the generation of network trapped into the local optimums and the iterations, the inertia weight were updated and the PSO was improved. The Elman weight and threshold were optimized by advanced PSO. Compared with the least squares, Elman and PSO-Elman by predicting the YC6G270-30 crankshaft pulse widths, the advanced PSO has simple structures and fast convergences. At the same time, the validity and practicability of the proposed method were verified.
    Prediction Model of Surface Roughness of 8418 Steel by EDM Based on SVM
    YU Jianwu;HU Qifeng;WEN Cheng;LIU Bo;SHEN Xiang
    2018, 29(07):  771-774,793. 
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    Because of the complexity of EDM processes, it took a great deal of time and high experimantal costs to study the effects of various discharge parameters and non-electric parameters on Ra of the workpieces. Based on SVM, a model was proposed to predict the surface roughness of workpieces after EDM, and genetic algorithm was used to optimize the parameters of the model to predict the surface roughness machined by different electrical discharge parameters. An EDM experiment was applied on 8418 steel to verify the accuracy of prediction model of surface roughness by comparing the predicted values with the experimental ones. Finally the errors analysis were carried on, and the maximun error of model is 2.27%.
    Influences and Evaluation Method of On-board Equipment on Metro Car Floor Vibrations
    WANG Yongsheng1;DING Jie1,2;ZANG Xiaobin1;LIU Haitao1
    2018, 29(07):  775-780. 
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    Through the workshop and loading vibration tests and analyses of a metro vehicle auxiliary converter, the floor vibration causes of metro car were determined, and the irrationality of on-board equipment vibration evaluation index was verified. A method was proposed to evaluate the influences of on-board equipment such as converters on the floor vibrations of metro car floors in the workshops or the laboratories. Test results show that the evaluation method errors are about 10%. The method may guide the selection of main vibration components such as transformers, fans, etc., and avoid the emergence of large quantities of vibration faults.
    Study on Deep-hole Axis Deflections Based on Elastic-plastic Deformations of Self-directed Pairs
    PANG Junzhong;LI Pengfei;HUANG Xiaobin
    2018, 29(07):  781-785. 
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    Based on the self-directing mechanism, the loads and contact states of the guide pairs were analyzed. By using Hertz contact theory and the elastic-plastic contact deformation theory, the deformation model of self-directed pairs and the mathematical prediction mode of deep-hole axis deflections were established. Combined with the theoretical model and the drilling experiments, the contact states of the guide pairs in the drilling processes were determined. The influences of the hysteresis of guide bar and the workpiece materials on the axis deflections were studied. The research results show that the greater hysteresis, the greater axis deflections; the smaller stiffnesses of the material, the greater axis deflections.
    Design of Centroid Parameters of Dummy Heads Models Based on Chinese Anthropometric Dimensions
    YAN Lingbo1;ZHANG Weifeng1;CAO Libo1;TANG Jun2;DAI Hongliang1;ZHANG Kai1
    2018, 29(07):  787-793. 
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    Based on the Chinese anthropometric dimensions,the finite element(FE) models of Chinese 50th percentile human body sizes dummy heads were developed by scaling the Hybrid Ⅲ dummy heads using non-uniform linearity scaling method.The head calibration was simulated to study the influences of centroid parameters on the dynamic responses.The design basis was discussed by comparing the results of Chinese dummy heads and Hybrid Ⅲ heads. The results show that the peak accelerations of Chinese dummy heads are as 8.6% larger than that of Hybrid Ⅲ dummy heads. The effects of the centroid parameters on the peak accelerations for Chinese dummy heads are larger than that of Hybrid Ⅲ dummy heads. The current requirements of the center of gravity(CG) of Hybrid Ⅲ dummy heads are not applicable to the designs of Chinese dummy heads, and more rigorous requirements should be needed for the manufacture of Chinese dummy heads.
    Time-dependent Reliability Analysis for Structures under Multi-level Loads and Cumulative Damages
    SUN Jianping1,2;TANG Zhaoping1,2;LUO Yiping2
    2018, 29(07):  794-803. 
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    Under the functions together with various kinds of uncertainty factors and time factors in the service environments, strength degradation and cumulative damages on structures would be conducted, and thereby seriously affected the structural reliability. The traditional reliability model could not reflect the influences of loading sequence and strength degradation. The problems of the multi loads equivalent transformation were studied herein by using interval theory and considering nonlinear evolution phenomena of fatigue damages caused by the different loading sequences. Aiming at the strength degradation structures under the multi-level loads, the dynamic non-probabilistic reliability prediction model was established and the analytical method of time-dependent reliability was constructed based on an interval model. Finally, by calculating an example, the time-dependent reliability for structures under multi-level loads was analyzed, and the validities of the method and model were verified.
    Research on Vehicle Stability under Crosswind Conditions by Dynamic Coupling Method
    LUO Zexuan1;GU Zhengqi1,2;HUANG Taiming1;FENG Chengjie1;LI Shuya1
    2018, 29(07):  804-810. 
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    For the study of vehicle stability under crosswind conditions, through the analyses of computational fluid dynamics(CFD) software FLUENT dynamic meshes and UDF, a dynamic coupling method was proposed combined with two-way coupling communication technology. The aerodynamics with vehicle dynamics was coupled. And the simulation results of dynamic coupling were compared with that of traditional static coupling. The influences of different wind speeds on vehicle crosswind stability were analyzed by dynamic coupling method.The calculation results indicate that vehicle stability under crosswind conditions by dynamic coupling method is worse than that by static coupling method, and the vehicle crosswind stability decreases with the increase of crosswinds.
    Experimental Study on Normal Dynamic Contact Stiffnesses of Trail Interfaces under Lubrications
    REN Peng;WANG Lihua;WANG Chunfeng
    2018, 29(07):  811-816. 
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    A fractal contact model of cylindrical micro convex body was established, and the contact of the two planes were replaced by cylindrical asperity contacts in the micro levels, which were more in line with the actual grinding surfaces. In the dynamic signal test system, the dynamic characteristic parameters of the interfaces were tested. The normal dynamic contact stiffnesses were obtained exactly and the influences of loads, speeds, and lubrications on the dynamic stiffnesses were analyzed. The experimental results show that increasing the fluid films, decreasing the sliding speeds and increasing the loads may improve the normal dynamic contact stiffnesses of the trail interfaces.
    Influences of Cutting Shapes of PDC Bits on Rock Breaking Efficiency
    ZHU Xiaohua;YI Qinjian
    2018, 29(07):  817-823. 
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    According to the elastic-plastic mechanics and rock mechanics, the Drucker-Prager criterion was used as the rock constitutive relation and the shear criterion was used to predict damage initiations. Based on the feasibility of rock model and PDC cutter-rock modeling method, a three-dimensional simulation model of cutting shapes rock with a PDC cutter was established, and the influences of cutting areas, the back rake angles and side rake angles of the PDC cutters on rock breaking efficiency were studied for different confining pressures. The results show that reducing the cutting shape areas under any confining pressures is benefit to rock breaking, and the wide cutting shapes may be used in PDC bits. Compared with the side rake angles of the PDC cutters, the back rake angles of the PDC cutters have greater effects on rock breaking efficiency, and the optimal back rake angle is as 5° at low confining pressure and is as 20° at high confining pressures.
    Failure Risk Analysis of EMU Pantograph Systems
    QI Jinping1, 2;LI Xingyun1
    2018, 29(07):  824-828. 
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    Aiming at the actual situations of data losses, multi-source heterogeneity and cognitive uncertainty in the failure risk analysis processes, polymorphic fuzzy Bayesian network was constructed to analyze failure risks of the system using fuzzy fault tree. According to the fuzzy fault probabilities of each root node, the fuzzy possibilities of the intermediate nodes and the leaf nodes were calculated under different fault states. Meanwhile the sensitivity of each nodes was analyzed, and the practical significance was explained. Finally, failure risk analyses of the pantograph systems were carried out according to the above mentioned. The analysis results show that the damages of the net pressure transformer, the fatigue cracks and the duct damages of the control valve plate are high risk events, which are consistent with the actual situations. At the same time, the method also extends the applications of the Bayesian network in practical engineerings.
    Effects of Induction Brazing Temperature on Grinding Performances of CBN Grinding Wheels
    REN Huizhong;LI Qilin;LEI Weining;DING Kai;ZHANG Suorong
    2018, 29(07):  829-834,841. 
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    CBN grinding wheels were made under the conditions of different brazing temperatures by ultra-high frequency induction brazing. The new compound morphologies were observed and analyzed by scanning electron microscope(SEM) and energy disperse spectroscope(EDS). The grinding performances of the brazed CBN wheels were evaluated by comparing with the electroplated CBN wheels. The results show that, N, B and Ti three elements were contained and formed at CBN interfaces, active element Ti was diffused and the chemical reactions occured with elements N and B. The grinding forces and the grinding specific energy of the CBN brazed wheel were smaller and abrasive surfaces were covered by compounds when the induction brazing temperature was as 940℃. The wear forms of electroplated CBN wheels and induction brazing CBN wheels were compared under the same grinding parameters, the phenomena indicate the wear forms of electroplated CBN wheels caused by the adhension and the wear forms of induction brazing CBN wheel caused by the fracture.
    Nonlinear Modeling and Parameter Identification of Hysteresis Characteristics on Piezoelectric Actuator Based on LS-SVM
    QIAN Cheng;HU Hongsheng
    2018, 29(07):  835-841. 
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    In order to identify hysteresis characteristics of piezoelectric actuators in the processes of applications, the hybrid modeling method of Preisach model and LS-SVM was adopted. Initial weighted coefficients in α-β plane were calculated based on Preisach model  through first order reverse curves. Centroid of hysteresis units and initial weighted coefficients were used as inputs and outputs of the LS-SVM which optimized by genetic algorithm. The finer weighted coefficients were calculated based on the optimized model and desired hysteric model was set up. Through the contrast between results of simulated model and the experimental results, errors stay between 0.12%~2.01%. Results show that the established model may accurately describe the hysteresis non-linearity of piezoelectric actuators and the proposed method is a practicable method.
    Modeling Method for Tool Wear Prediction Based on ADNLSSVM
    XIAO Pengfei1;ZHANG Chaoyong1;LUO Min1;LIN Wenwen2
    2018, 29(07):  842-849. 
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    In the building process of a tool condition prediction model with traditional machine learning methods, the limited number of available training samples and the fixed length of the sliding time window and prediction model resulted in lower modeling accuracy and efficiency. Dynamic model was set up to monitor the tool wear states by using an ADNLSSVM. Feature vectors were extracted by time-frequency-domain analysis from data set of open database of milling processes, and parts of them were selected by correlation analysis as model inputs. The experimental results shows better modeling efficiency and prediction accuracy.
    Optimal Deployment of Networked Manufacturing Resources Based on TPS Hierarchical System
    LIU Xiaoyang;LIU Enfu;FANG Yixiang;LIU Zhenyu;JIN Jiangyan
    2018, 29(07):  850-859. 
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    An optimal method of networked manufacturing resources configuration was presented based on TPS hierarchical system. TPS hierarchical system included logical relations layers and logical reasoning layers. Logical relations layers described manufacturing task informations, manufacturing resource informations and their matching relation informations, and a unified mathematical model with TPS was built. Logical reasoning layer completed data calculations and optimizations with TPS fuzzy mathematical models and reasoning mechanism, and rough set hierarchical analysis was used to achieve the manufacturing resources optimization deployments of multi-objective decisions. Finally, the feasibility and effectiveness of the method was verified by a typical case.
    Design of Needle Free Injectors Driven by Electromagnetism and Their Mechanics and Motion Simulations
    CHEN Tianyu1;WANG Mingdi1;CHEN Jie2
    2018, 29(07):  859-863. 
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    For heavy, unsustainable uses and other shortcomings of the widely used mechanical and pneumatic needle-free injectors, a needle-free injection was proposed by using an electromagnetic drive DC power supply devices; the electromagnetic needle-free injection systems were divided into electromagnetic portions and the fluid portions, and mathematical models were established to derive the corresponding formulas and numerical calculations. The electromagnetic forces and the fluid parts of the simulation analysis, the graph of the current, the relative position of the core and electromagnetic forces, and the diagram of ampoules thrust rod ejection outlet pressure and fluid velocity were obtained. The results show that: the needle free injector have enough power to meet the design requirements, ampoule injection pressure and speed of the jet meet the requirements of entering human skin surfaces.
    Modeling of Punching Processes of Resistance Element Welding of Aluminums and Steels
    HE Guanzhong1,2;LOU Ming1,2;MA Yunwu1,2;LI Yongbing1,2
    2018, 29(07):  864-869,881. 
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    Addressing to the punching phase of resistance element welding (REW)processes, a two-dimensional axisymmetric finite-element model was developed, through which the geometrical evolutions and stress distributions of joints were studied. Moreover, the influence rules of five geometrical parameters on punching processes and joint qualities were analyzed, which consisted of rivet head shapes, rivet shank shapes, boss heights, boss widths and the gaps between rivets and dies. Some optimization suggestions of geometric shapes of the rivets and dies were also proposed.
    Research on Q235/AA5052 Clad Convex Tubes Prepared byGranule Medium Bulging Processes
    DONG Guojiang;CHEN Mengjie;ZHU Liangjin;DU Jian;LIU Zhilei
    2018, 29(07):  870-878. 
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    The inner AA5052 extruded tubes of steel/aluminum clad tubes were difficult to coordinate with the outer tube deformations to the target tube shape requirements for its poor forming performance at room temperature. Based on this point, a new project of aluminum alloy tube annealing treatment, assembly and granule medium bulging processes was proposed on clad tubes. Ω shape clad tubes satisfied with industrial requirements were prepared successfully by the processes. The bulging ratio reached 1.40, diameter-thickness ratio was as 3/102 and the maximum thinning rate was less than 20%. The experimental researches show that the plastic deformation capacity of AA5052 extruded tube nearly reaches the maximum value and the elongation rate increases by more than 3 times when the annealing treatment is at 440 ℃ for 60 min. The distributions of wall-thickness are related to the friction coefficients between tube layers during the bulging processes. Reducing the friction at Q235/AA5052 interfaces is beneficial for preventing  decrease of wall-thicknesses and improving bulging limit of clad tubes. The expansion processes of granule medium have low requirements for the dimensional accuracy of tube blanks. And this processes may be realized by universal equipment and simple dies.