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Table of Content

    10 April 2019, Volume 30 Issue 07
    Measurement Model of Fault Severity for Components Considering Common Cause Faults
    CAO Yingsai;LIU Sifeng;FANG Zhigeng;DONG Wenjie
    2019, 30(07):  757-762. 
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    To measure the severity of component's single faults with the consideration of common cause faults, the components were taken as the participants and the alliances were considered as the common cause component groups by using cooperative game theory, a Shapley value measurement model of component fault severity was proposed considering common cause faults. Firstly, a nonlinear transformation function of fault severity level was established, aiming to improve the grade-based fault severity measurements. Secondly, a method of measuring the joint severity of common cause failures was developed according to the characteristics of common cause faults, and then the expected contribution of each components to the all common cause fault severity was calculated with the determination of the types and numbers of common cause component groups. At last, a case of spindle system in CNC machine was presented to demonstrate the effectiveness of the proposed model. The influences of nonlinear transformation function as well as the common cause faults on the fault severity measurements were also investigated in the case.
    Parameter Optimization and Experimental Comparison of Two-speed Pure Electric Vehicle Transmission Systems
    SHENG Jixin1;ZHANG Bangji1;ZHU Bo2;WANG Ming1;JIN Qiutan1
    2019, 30(07):  763-770,776. 
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    To improve the driving efficiency of pure electric vehicles, by using the transmission scheme of two-speed automated mechanical transmission(AMT), a parameter matching model of multi-objective genetic algorithm was developed based on a two-block dual clutch transmission(DCT) electric vehicle. The peak power and peak torque of motor were taken as the integrated design goal. Meahwhile, the parametric matching design of motor was carried out with the vehicle dynamic index as the limited conditions. To improve the pure electric vehicle driving ranges and optimize the transmission system's efficient working ranges, the minimum power consumption of vehicle integrated conditions was chosen as the design goal. Based on the constraint conditions of vehicle dynamics and ride comfort indexes, a global optimization genetic algorithm was used to optimize the pure electric vehicle performance with two-speed ratio transmission. Then, the comparisons between the pure electric vehicle with AMT matching model and the DCT electric vehicle reference model were presented. The results indicate that the time of 100 kilometer acceleration for the optimized model is reduced by 5.79%, the new European driving cycle(NEDC) operating range mileage is increased by 0.31%, and the mileage of highway fuel economy test(HWFET) operating conditions is increased by 1.44%. Futhermore, it may be seen that the time of 100 kilometer acceleration is reduced by 10.31%, and the mileage of NEDC operating range is increased by 5.85% compared to the DCT reference model.
    Applications of Composite Laminated Structures in Anti-icing and De-icing Systems
    CHEN Bingbin;ZHANG Zheng;LU Congda;WU Huaping;CHAI Guozhong
    2019, 30(07):  771-776. 
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    A new anti-icing/de-icing system was designed based on composite layups. The multi-functional composite structures consisted of copper-based superhydrophobic materials, asymmetric cross-ply of bi-stable structures and polyimide heating films. Copper-based superhydrophobic materials played a role in delaying water droplets of icing, reducing icing capacity and the adhesion between ice and surface. When the bi-stable structures were driven using heating method by polyimide films, the heat could also melt the ice on the surface; the snap-through processes of bi-stable could generate mechanical vibration, which formed a thermo-mechanical coupling anti-icing and de-icing mechanism. The surface of system has good superhydrophobic characteristics with the water contact angle reaching 155°. Besides, the system has good deformability, resistance to high and low temperature alternating and ultraviolet(UV) resistance.
    Aerodynamic Drag Reduction Mechanism of Automobile Spoiler Based on Porous Media and Bionic Design
    YUAN Zhiqun1,2,4;GU Zhengqi3
    2019, 30(07):  777-785. 
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    In order to reduce the aerodynamic drag of conventional spoilers, two new structural schemes of porous medium spoilers and bionic spoilers were designed. The variation laws of aerodynamic drag of two schemes were analyzed under different yaw angles by computational fluid dynamics method, and the aerodynamic drag reduction mechanisms of two new structures were revealed. Compared with the conventional spoilers, the aerodynamic drag peak of two new structures were decreased by 3.3% and 4.7% respectively. A combined structure scheme of bionic spoilers and side skirts was designed to solve the problems of increasing aerodynamic drag caused by conventional spoilers at large yaw angles. Compared with the conventional spoilers, the aerodynamic drag peak of the combined structures decreased by 10.7%. The proposed method was validated by scale model wind tunnel test.
    Simulation and Optimization of Mechanics Behaviors of Top Drive Center Pipe Thread
    KUANG Yuchun;HUANG Hesong;MIN Taoyuan
    2019, 30(07):  786-793. 
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    Aiming at the problem of thread gluing, fracture of the threaded coupling in top drive center pipe thread, 2D and 3D finite element models under torques were established based on the virtual work principle, von Mises yield criterion and experimental results of constitutive model of central pipes. The reliability of finite element analysis was verified by the results of experimental and numerical simulations. The reliability 2D axisymmetric finite element model was illustrated by comparing of 2D, 3D results. The stress distribution and mechanics properties of the central pipe thread joints are obtained, which point out that the tightening torques have great influences on connection strength. Then on the basis of that combining with the field failures of the tool joints, the finite element sensitivity analysis on the three parameters including taper, pitch and effective thread length were carried out, and the optimal values among the parameters were recommended with the comprehensive considerations of connection strengths and production costs.
    Coupling Analysis of Product Family Design Based on Axiomatic Design and Modular Incidence Matrix
    CHENG Xianfu;QIU Haoyang;WAN Liyun;WANG Haolun
    2019, 30(07):  794-803. 
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    For the coupling problems of product family design, the similarities and differences of design coupling between product family and single product were analyzed and compared, and a method of analyzing and disposing coupling design for product family was presented based on axiomatic design and modular incidence matrix. The axiomatic design theory was utilized as framework to analyze and classify functional requirements. The corresponding relationships among customer's demands, functions, components and design parameters of product platform were analyzed, and the influences of adaptive design parameters were considered to be divided into two categories to identify commonality and differences of product family. This may weaken design coupling from strategic level of platform plan. In the view of platform operation level, according to comprehensive correlation degree among design parameters, any modules were generated by clustering reconstruction with less dependent degree in design structure matrix. The change propagation of design parameters were analyzed, and modular incidence matrix was established. Then from the coupling inside modules, and among design parameters with different modules, the detailed analyzing and disposing method was given. Finally, an example of electro-hydraulic disc brake was provided to illustrate the analysis and disposal processes on the proposed method.
    Lane Keeping Control by Considering Influences of Road Adhesion and Adaptive Time Coefficients
    FENG Pengfei1,2;JIN Huiqing1,2; WANG Huiran3;LIU Fayong4
    2019, 30(07):  804-811. 
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    The influences of road adhesion coefficients on vehicle control were analyzed. The vehicle-road dynamics model was obtained according to the vehicle linear two degrees of freedom models and certain preview informations. An estimation algorithm of road adhesion coefficients was presented based on Brush tire model,in view of the time delay between yaw speed and steering angle, an adaptive time coefficient related to the road adhesion coefficients was put forward and added to the vehicle-road dynamics model. Based on the sliding mode control theory, the yaw rate sliding mode controllers were designed to track the desired vehicle state and obtain an ideal steer angle. Finally, based on CarSim/Simulink simulation and HIL tests, the effectiveness of lane keeping control considering the adaptive time coefficient under different road adhesion coefficients are improved.
    Validation Method of Parameter Uncertainty Models for Response Accuracy
    XIANG Yongyong;PAN Baisong;LUO Luping;XIE Shaojun
    2019, 30(07):  811-817,824. 
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    Aiming at the problems of model validation for mixed uncertainty cases of probability and interval in parameter uncertainty models, a model validation method was proposed for response accuracy, and the specific implementation steps were described for the validation processes.Model validation criterion parameters were obtained by using the imprecise cumulative distribution function of response numerical results and empirical distribution function of response test results, then the model validation results were assessed. For the model that didn't satisfy the evaluation requirements, an optimization model was established, the maximum total confidence level of interval uncertainty parameters to be corrected was taken as the optimization object, the assessment standard of model validation and initial values of model parameters were used as constraint conditions, finally the optimization model was solved by the genetic algorithm and the corrected values of model parameters were obtained.The model validation method was applied to the Sandia thermal challenge problem, the results show that the proposed method may significantly improve the forecast accuracy and response accuracy, the results are credible.
    A Hierarchical and Simultaneous Gravity Unloading Testbed
    YANG Guoyong1,2;WANG Hongguang1;JIANG Yong1;LING Lie1
    2019, 30(07):  818-824. 
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    An APM was consisted of two orthogonal joints. To test the performances of APMs, a hierarchical and simultaneous gravity unloading method was proposed, and a gravity unloading testbed was built based on this method. The gravity of two orthogonal joints were unloaded and the rotational degree of freedom for both joints was offered by the air bearing gravity unloading testbed. The testbed was a two layers structure, and the combination of planar air bearing and air spindle was used to unload gravity, which provided the two degrees of freedom to allow the rotation of APM. The payload test might truly show the performance of APMs, so the artificial payload was designed with the constraints of moment of inertia and frequency. This artificial payload was fixed on the gravity unloading testbed. The coupling problems of moment of inertia of both axes were solved and the frequency requirements were satisfied. The gravity unloading testbed was established and tested based on the analysis of gravity unloading method and design of the artificial payload. The testing results show the effectiveness of the hierarchical and simultaneous gravity unloading method.
    Modeling, Simulation and Tests of Friction Characteristics for Synchronizers
    ZHANG Zhigang;YU Xiaoxia;ZHENG Yanjie;LI Teng
    2019, 30(07):  825-831. 
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    Synchronizer had experienced hydraulic friction, mixed friction, solid friction for three stages in the synchronization processes. In order to analyze the synchronization process of synchronizer effectively, the mathematical models were established for three stages respectively. A co-simulation model of synchronizer was established by using AMESim and MATLAB-Simulink modules in working processes, and the simulation analysis and test verification were carried out. The research results show that the model may accurately simulate shift forces, shift displacements, synchronization torques and transmission input speeds.The calculation errors of synchronization time are less than 9.58%.
    Stress Analysis of Micro Movable Teeth Transmission Systems Considering Van der Waals Force
    CAO Fulin;SHI Xufei;XU Lizhong
    2019, 30(07):  831-839. 
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    A micro-integrated movable tooth transmission system was introduced herein and the working principles were introduced. The static equations of any movable teeth at different meshing positions in micro-scale were deduced. The Van der Waals forces on movable teeth were solved by Van der Waals potential functions. The variation of the forces acting on the movable teeth from the wave generator, the movable tooth rack and the center wheel was studied when considering the Van der Waals forces. By using the Hertz theory, the forces of the movable teeth from the wave generator, the contact stress were deduced theoretically and the effects of different geometric parameters of the microstructure on the forces and contact stress of the movable teeth were studied.
    Prediction of Disassembly Costs of ELVs by Fuzzy Clustering Based on Disassembly Difficulties
    ZHANG Chunliang;CHEN Ming
    2019, 30(07):  840-845. 
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    Aiming at the problems of cost evaluation before dismantling ELVs, a general comprehensive cost evaluation model was established based on disassembly difficulties and fuzzy clustering. The factors affecting disassembly difficulties of ELVs were put forward. The fuzzy clustering analyses were used to determine the components that had the same disassembly difficulty among the disassembly of different models. An error evaluation method of the disassembly costs was given about the cluster model. Taking the experimental data of physical dismantling of four scrapped experimental vehicles(two cars, one sport utility vehicle, and one multi-purpose vehicle) as examples, a general disassembly cost model was quantified and evaluated based on fuzzy clustering. The results show that the model has the commonality of various models and the maximum error of disassembly cost is less than 28%. The disassembly cost forecasting model helps the technological decision before ELV dismantling in methodology.
    Multidisciplinary Optimization for Steel-Aluminum Composite Frames Considering Vibration Characteristics
    SONG Yanli1,2;XU Qinchao1,2;XU Fengxiang1,2;RUAN Shili1,2;SU Jianjun3;WANG Lianhao3
    2019, 30(07):  846-851,876. 
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    A pure electric light truck frame was taken as the research object, an orthogonal test method was used to carry out the significant analysis of the part materials to the frame performances and the replacement scheme of high strength aluminum alloy sheets was determined, and thus the steel-aluminum composite frames were obtained. In order to preclude the resonance of steel-aluminum composite frames and cabs, a multidisciplinary optimization model was adopted to optimize the multi thickness matching for the steel-aluminum composite frames considering both the static stiffness and the dynamic frequency. It is shown that in the premise of performance guarantees, the lightweight frame's fourth-order frequency is increased by 1.5 Hz, avoiding the dangerous frequency. The frame weight was reduced by 13.5 kg, accounting for 7.2% of the original pure steel frames.
    Effects of Surfactant on Performances of Atomized Nano Cutting Fluid after Ultrasonic Dispersion in Abrasive Cutting-grinding
    MENG Zhen1,2;CUI Zhi1;NI Jing1,2;YANG Yongfeng1,2
    2019, 30(07):  852-857. 
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    In order to analysis the effects of the surfactant on the performances of atomized nano liquids after ultrasonic preparation, by using grinding wheel cutting-grinding machine, a comparative cutting experiment was carried out with dry cutting, as well as the four different kind of atomized cutting fluids, high water-based fluid, water-based fluid + surfactant, water-based fluid + graphene particles and water-based fluid + surfactant + graphene particles respectively. The experimental results show that the atomized liquid may effectively reduce the grinding cutting forces and the surfactant played a better role in lubrication by reducing the atomized droplet wetting angle(maximum reduction of 24.9%) to improve the dispersion of graphene particles in cutting fluid. And compared with high water atomized liquid, surfactant may further reduce the tangential forces by 35.4% and the normal forces by 57.2% at the beginning of the cutting processes.
    Gas Field Simulation and Flow Channel Structure Optimization of SLM
    LIANG Pinghua1;Tang Qian1;YU Zhiqiang2;FENG Qixiang1;LIU Wei1
    2019, 30(07):  858-863. 
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    Aiming at the black smoke residue phenomenon during SLM processes, the gas field in the cross sections of inert gas supply channels and the black smoke generation zones in the forming chambers of a SLM system called E-Plus-M250 were simulated using ANSYS ICEM CFD and ANSYS FLUENT. The structures of the inert gas supply channels were optimized based on the simulation results. The simulation results show that the residual black smoke on the powder beds of the forming chambers is caused by the uneven distribution of the gas field in the laser scanning areas. Based on the simulation results and through sever improvements to the structures of the gas supply channels, the standard deviation of the air velocity distribution at the air inlet cross sections is reduced from 0.472 7 to 0.182 1, which is in good agreement with the flow fields of the forming chambers. The experiments verify the effectiveness of the optimization scheme, which means that the optimized flow channel has the capability of removing the black smoke more effectively when the metal powder is melted in the forming chambers.
    Printing Orientation Analysis of Model 3D Printing Based on Minimum Theory Support Volumes
    JIANG Xiaotong1;GUO Baosu2;PENG Qingjin3;LIU Deli1
    2019, 30(07):  864-871. 
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    In the 3D printing processes, aiming at the problems that the support volumes of the model needed to decrease after printing,the relationships between the printing orientations and the support volumes were studied, and a method to search the printing orientations toward the minimal theory support volumes was developed. First, the background of theory support volumes of discrete grid models was introduced, and a calculative method was suggested to minimize the theory support volumes. Second, the continuity of the theory support volume functions was analyzed to overcome the discontinuity problems of the functions. A derivative-free optimization algorithm was proposed to obtain the correct orientation of minimum theory support volumes. Experiments show that the proposed algorithm may accurately calculate the correct orientations corresponding to the theory support volumes.
    Optimum Design of Roller Wheel Structural Parameters for Unequal-thickness Blanks Tailored Laser Welding
    CHEN Dong1;XU Min2;LI Zhi3;GUO Song1;GAO Yankai1
    2019, 30(07):  872-876. 
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    Rolling technology was an effective way to solve the gap problems of unequal-thickness blanks tailored laser welding, the rolling wheel was the core of the rolling mechanisms, and the structural parameters directly affected the rolling effectiveness. Through the simulation analyses of the rolling processes, the relationship among the rolling wheel parameters and the width spreads, the rolling forces was determined. Based on the experimental data of the simulation experiments, the RBF neural network model of the rolling mechanisms were established by learning and training. Based on the model, 10 000 experimental data were obtained. On the basis of these large data, the structure parameters of the rollers were optimized with smaller rolling forces and wider width spreads. Based on the optimization results, the rolling mechanism was designed, and the welding effectiveness and the welding effectiveness after rolling were verified.
    Research on Single-side Magnetic Assisted Resistance Spot Welding Process of Stainless Steel
    XU Ye1;QI Lin2,3;HAN Xiaohui1;YE Jiehe1;LI Yongbing2,3
    2019, 30(07):  877-881. 
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    In order to improve the single-side welding joint quality and reduce the welding defects, a single-side radial magnetizing device for single-side resistance spot welding equipment was designed based on the traditional double-side axial magnetizing device. Compared with the traditional resistance spot welding ,the variations of traditional resistance spot welding joints and magnetic assisted resistance welding joints with welding current were studied. The mechanism and effectivenesses of single-side magnetic assisted resistance spot welding on nugget morphology, nugget size, microstructure and mechanical properties were revealed ,and the feasibility of single-side magnetic assisted resistance spot welding process was verified.