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Table of Content

    10 October 2019, Volume 30 Issue 19
    Shakedown Analysis of Elbow Pipes of Nuclear Power Plants under Cyclic Loading Based on LMM
    CHEN Xiaohui1;CHEN Haofeng2;CHEN Xu3
    2019, 30(19):  2269-2275. 
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    Ratcheting effect experiments of 90° elbow pipes under internal pressure and in-plane bending were carried out for nuclear power plants herein, and then the limit load, shakedown load and ratcheting boundary of 90°elbow pipes were studied by numerical method. First, based on twice elastic slope criterion and tangent intersection criterion, limit load of 90° elbow pipes under internal pressure or in-plane bending was determined by ideal elastic-plastic finite element analysis. Meanwhile, limit load and shakedown load of 90°elbow pipes under internal pressure alone or in-plane bending alone and the interaction between them were determined by LMM. Again, ratcheting boundary of 90°elbow pipes was determined by Ohno-Wang model combining with C-TDF and LMM. Finally, ratcheting boundaries of 90°elbow pipes determined by two methods were compared. The results indicate that the errors of limit load determined by twice elastic slope criterion, tangent intersection criterion and LMM are as 10.78%. It is also showed the efficiency and rapidity of LMM. The ratcheting boundary determined by both methods were compared, the results are well consistent when internal pressures are in the range of 20 MPa and 35 MPa, the trends of predicted results of both methods are different when internal pressures are less than 20 MPa.
    Two-way Coupling Analysis of Vehicle Stability in Different Crosswind Conditions
    LI Shuya1;GU Zhengqi1,2;HUANG Taiming3;LIU Jun1;ZHENG Ledian1
    2019, 30(19):  2276-2286. 
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    In order to study the vehicle stability in natural crosswind, a real-time two-way coupling approach was established, which coupled the vehicle aerodynamics with vehicle multi-body dynamics. And the aerodynamics simulation method was verified by wind tunnel tests. The robustness of vehicle multi-body dynamics model was analyzed with the translation of pressure center. According to the requirements of ISO12021, the moving boundary method was used to investigate the necessity to conduct the two-way coupling by comparing the results of the both methods. Then the vehicle stability in different crosswinds was discussed with the comparison of natural crosswind conditions and ISO12021 conditions. The results show that the change of the vehicle posture in crosswind conditions will also affect the flow fields around the vehicle in turn, especially the flow field on the vehicle bottom and windward side. The vehicle motion is affected by the combined effects of crosswind and suspension. It is essential to conduct the two-way coupling to study vehicle crosswind stability. The impacts of natural crosswinds on the flow fields around the vehicle are faster and more unstable than that of the standard conditions. And the unstable flow field leads to peak aerodynamic forces, which make the vehicle stability worse in natural crosswinds than that in standard crosswind conditions. The evaluation of vehicle crosswind stability needs to consider the influences of different crosswind conditions.
    Influence Analysis of Piston Structures on Heat Transfer and Strength
    WEN Jun1,2;LEI Jilin1;DENG Xiwen1;WANG Dongfang1;WEN Zhigao2;LI Zhekun1
    2019, 30(19):  2287-2293. 
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    The pistons of a high pressure common rail diesel engine that met state-Ⅴ emission standards were taken as the object of study. The steady-state temperature field distributions and heat loads of the pistons under the rated power conditions were analyzed by hardness plug temperature measurement method. Based on the test results of temperature field tests, the numerical simulation models of fluid-solid coupling heat transfer of internal cooling oil and piston were set up. The influences of the four piston structure parameters (the piston pin length, the pin hole diameter, the height of the fire bank and the center distance of the oil return hole) on the piston heat transfer and structural strength were analyzed by simulations. The results show that the heat flux density of the piston fire bank, the inner chamber, the oil return hole and the pin hole is greater and the stress concentration were appeared. The four parameters of the piston pin length, pin hole diameter, height of the fire bank and the center distance of the oil return hole were selected to further study the influences of the piston structures on the heat transfer and structural strength. The simulation results also show that each changes in the structures of the pistons will change the heat transfer performances and stress distributions, and will cause the stresses and temperatures of other key points to change, which makes the modification of the piston structures should be more cautious. Appropriate increase pin length, pin hole diameter and fire bank thickness, reduce the center distance of the oil return hole, may improve the piston heat, and reduce the stress of the pistons.
    Assembly Variation Analysis of Compliant Parts Based on Mesh Deformation
    SU Chengyang;WANG Zhiguo
    2019, 30(19):  2294-2300. 
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    The sensitivity matrix of traditional finite element methods were derived from the product theoretical mathematical model in assembly deviation analysis of compliant parts. However, analysis results computed by traditional methods were inaccurate because of the shape errors between theoretical mathematical model and actual mathematical model. An improved method of assembly deviation analysis was presented herein. To obtain fitting model whose shape was close to actual mathematical model, mesh deformation was used to change the shape of theoretical mathematical model based on error source data of key points. The assembly spring back test of metal sheet and the assembly deviation analysis and calculation of aircraft panels were carried out. Different kinds of analysis results were obtained and compared by means of simulation, test and measurement. Result shows that the analysis error obtained by the improved method may be controlled to less than 5%.
    Integrated Factor Reliability Allocation Method Considering Influences of Two-layer Factors
    ZHANG Qiang;LI Jian;XIE Liyang;HE Xuehong
    2019, 30(19):  2301-2305. 
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    In order to deal with the reliability allocation problem considering multi-layer factors of complex mechanical systems, the traditional integrated factor reliability allocation method was analyzed, an integrated factor reliability allocation method was proposed considering the influences of two-layer factors. In this method, the levels of traditional reliability influencing factors were divided, a global index mathematical model was established considering the influences of two-layer factors, and then the global index weights of each subsystem were determined, the reliability of each subsystem was allocated. Finally, an engineering case was given to illustrate specific applications of the method and the simplicity and effectiveness.
    Study on Static and Dynamic Characteristics of Mechanical Elastic Wheels
    ZHAO Youqun;BAI Yiqiang;YE Chao;DENG Yaoji;XU Han;WANG Qiuwei
    2019, 30(19):  2306-2312. 
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    In order to reveal the performance characteristics of mechanical elastic wheels, the static and dynamic characteristics of mechanical elastic wheels were studied based on mechanics theory and virtual prototype technology. The static loading characteristics of mechanical elastic wheels were analyzed comparatively under good conditions and with a hinged group damaged conditions. The results show that the maximum tensions of hinged group under damaged condition are quite different from those under intact condition. They are no longer located at the top of the wrestle wheel, and the maximum tension value is much higher than that under intact condition. The mechanics model of the driving wheel, driven wheel and brake wheel were established under dynamic conditions. Also, the wheel hub, hinged group and elastic wheel disk force transmissions were analyzed. Finally, the vehicle model with the elastic wheels was established in ADAMS and the simulation study was carried out. The results verify the natural relation among the rotational hysteresis angles of the mechanical elastic wheels and input torques, speeds and ground tangential forces.
    Improvement and Performance Testing of McKibben Pneumatic Muscle Model
    GUO Zhenwu;HUANG Jiqing;WANG Feiyang;WANG Binrui;CHEN Dijian
    2019, 30(19):  2313-2318,2328. 
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    The braided sleeve pneumatic muscle model was studied and improved, with which a braided sleeve pneumatic muscle was made. Firstly, to solve the empirical coefficients in the model, the least squares errors between the model and experiments were optimized by the trust-region algorithm. Then, the effects of structural parameters of the initial weaving angle and rubber tube wall thickness on performance were analyzed. Finally, according to the analysis results, structural parameters were selected and both end structures were designed, and braided sleeve pneumatic muscle was self-made. Simulation coincided with experimental results, which confirmed the validity of model that improved the accuracy. It is obviously shown that the performances of braided sleeve pneumatic muscle self-made are improved a lot with control experiments, which also demonstrates the effectiveness of improving the performance of braided sleeve pneumatic muscle with the guidance of the model.
    Research on Influence Factors for Residual Strengths of Fiber Metal Laminates in Rivet
    CHENG Lipeng1;PING Xuecheng1,2;WANG Chunguang1;GUO Qian1
    2019, 30(19):  2319-2328. 
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    In order to study coupled damage of fiber metal laminates in a riveted single lap joint, a progressive failure model for fiber metal laminates was established by using the Johnson-Cook failure criterion for metal, the 3D Hashin damage criterion for fiber reinforced composites, the traction-seperation law for interface delamination and the stiffness degeneration theory of composites. The effectiveness of the present models were verified by experiments. The effects of the secondary bending, aluminum alloy fraction, pretightening forces, hole-edge distances on riveting strength and failure mode of fiber metal laminates were investigate to provide feasible suggestions for the design of riveted single lap joints of fiber metal laminates. The following conclusions are drawn: (1)The secondary bending speeds up laminate damage and reduces the riveting strength of laminates, and medium eccentric loading may weaken secondary bending and improve riveting strength better; (2)The increase of aluminum alloy fraction may improve the residual strength of laminates, but when it is greater than 50%, the specific stiffness and strength of the laminates will decrease; (3)The increase of pretightening forces may delay the damage initiation of fiber and matrix, and enhance strength of the riveted joint, thus improving the damage resistance of laminates; (4)With the increasing of the hole-edge distance, the residual strength of the riveted joint is improved, and the failure mode transform from catastrophic net-tension failure mode gradually into an ideal crushing failure mode, but when the hole-edge distance reaches a certain value, the residual strength is no longer significantly improved, and the laminate maintains crushing failure modes.
    Design and Optimization of Forklift Steering Mechanisms with Horizontal Hydro-cylinder
    YING Fuqiang;MA Liangliang;WANG Neili
    2019, 30(19):  2329-2334,2341. 
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    In order to solve the problems that the forklift might not steer in situ or steer heavily, based on the existing electric forklift horizontal hydro-cylinder steering system, a new type of space steering system was developed, and  the mechanical model was established. Parametric design was carried out in the virtual prototype, with the goals of the stresses of steering cylinder piston rods, steering errors and interference gaps in steering processes, multi-objective optimization was carried out by using Insight module. According to the optimization results, the model was modified and the final model was determined, the turning radius measurement and energy-saving experiments were conducted finally. Test results show that the optimized steering system may realize pivot steering with the improved force conditions of the steering.
    Optimization Design of Hoist Towers Based on Dynamic Kriging Model with Double Point Adding Criterion
    CHEN Peng;ZHANG Qing;HUANG Lei
    2019, 30(19):  2335-2341. 
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    In order to minimize the weight of hoist towers under the conditions of satisfying the strength requirements and solve the problems that traditional Kriging model could hardly guarantee the global accuracy and local accuracy simultaneously, a dynamic Kriging model with double point adding criterion was put forward. Based on the model and artificial bee colony algorithm, the hoist towers were optimized. The sensitive parameters determined by global sensitivity analyses of hoist towers were regarded as design variables, then the initial Kriging model was established by sample data obtained by the Latin hypercube experimental design. The maximum stress was taken as constraints. During the optimization processes, double point adding criterion was used to update Kriging model continuously for the sake of higher global accuracy and local accuracy at the optimal solutions until obtaining optimal solutions. The research results show that the weight of hoist towers is reduced by 39.37% after optimization while the maximum stress is unchanged. The optimization efficiency is greatly improved based on the dynamic Kriging model with double point adding criterion in comparison with simulation model. The dynamic Kriging model with double point adding criterion has higher global accuracy, local accuracy and local accuracy at the optimal solutions compared with static Kriging model and dynamic Kriging model with traditional adding criterion.
    Experimental Study on Nano-CMQL Grinding of Bearing Steels
    ZHANG Gaofeng;LI Jingtao;WANG Zhigang;CHEN Wenxin
    2019, 30(19):  2342-2348. 
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    Nano-CMQL was an efficient and environmentally friendly lubrication technology that combined the cryogenic minimum quantity lubrication with lubrication oil containing nanoparticles. The GCr15 hardened bearing steels were machined by using aluminum oxide grinding wheel with 60# ceramic bond. The normal grinding force, specific grinding energy,grinding temperature,sub-surface damage and roughness were compared under different grinding parameters under four different grinding conditions which were dry grinding conditions, pour grinding conditions, cryogenic cold air minimum quantity lubrication (CMQL) and Nano-CMQL. The results show that Nano-CMQL, which is prepared by way of adding MoS2 solid particles with particle size 40 nm to the basic grinding fluid, may reduce the normal grinding force and grinding temperature effectively in grinding processes, and has better grinding performances under higher grinding speeds and deeper grinding depths.
    Green Performance Optimization of Mechatronic Products Based on Green Features and QFD Technology
    WANG Liming1,2;LI Long1,2;FU Yan1,2;LI Fangyi1,2;PENG Xin1,2;WANG Geng1,2
    2019, 30(19):  2349-2355. 
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    The concept of green features was proposed, and the qualitative and quantitative green features in the product life cycle were quantified herein. Aimed to the customer satisfaction with green products, through the green QFD, the green demand analysis was mapped to the green characteristics of the product life cycle, and an optimization model with green demand satisfaction as the goal was established. By optimizing the configuration to adjust the amount of green feature changes, the key technical characteristics of the limited enterprise resources were optimized and improved, achieving the maximum satisfaction of customer demands and ensuring the green performance of the products. Taking a hobbing machine as an example, the feasibility and effectiveness of the proposed method were verified.
    Research on Energy Management Strategy of Extended-program Hybrid Cleaning Vehicles
    GAO Aiyun;ZHANG Fengli
    2019, 30(19):  2356-2363. 
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    Aiming at the problems of poor emissions, high noise and serious pollution of the traditional dual-engine washing vehicles, an energy management strategy of steady-state distribution and dynamic coordination was put forward by using the extended-program hybrid power-sweeping vehicle power systems. Through the division of the working modes, a dynamic coordinated energy management method was designed based on engine fuzzy speed PID+ battery droop control. Taking the optimal fuel consumption as the control target, the balances of charges and discharges of the battery were maintained by controlling the engine power outputs and suppressing the fluctuations of charge-discharge powers, and finally the best fuel economy of the sweeping vehicles was achieved. Through simulation analysis, the results show that compared with the traditional dual-engine sanitation vehicles, the engine speed control is stable, the fuel-saving rate of the transition mode reaches 17.7%, and the fuel-saving rate of the sweeping mode reaches 37.1%, which verify the correctness of the control strategy.
    Research on AVPS Based on Scenario Driven and Hierarchical Planning
    QIU Shaolin;QIAN Lijun;LU Jianhui
    2019, 30(19):  2364-2371. 
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    Functional scenario of design and testing of the AVPS was initially defined, and the environmental models were set up based on the defined scenario. The functions of the AVPS mainly included the path planning layers and the behavior layers. Global reference paths of the AVPS were generated based on the V2I communication service and the Reeds-Shepp Car curves. The cubic spline fitting curves were used for path smoothing. The nonlinear constraint vehicle model, the preview control theory and dynamic surface control were used for design lateral controllers to achieve trajectory tracking. Finally, the function integration and validity verification of the AVPS were verified in the PreScan-MATLAB co-simulation environments.
    Research on Rotary Friction Riveting Technology of Heterogeneous High Performance Thermoplastic Materials
    LI Peng1,2;QIAO Fengbin2;WANG Fei2;QIU Lianfang2;WANG Jiang2; ZHAO Weigang2
    2019, 30(19):  2372-2377. 
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    The effects of friction riveting equipment different spindle movement parameters on the riveting-heading morphology of AA2024-T351/PEI ULTEM-1000 friction riveting processes were studied. The results show that the main technological parameters of riveting-heading are rivet rotating speed, riveting press-in speed, press-in distance and stop procedure speed. The higher the rivet rotating speed, the greater the heat input in the friction riveting connection area. If the riveting press-in speed is too small, the rivet will gradually penetrate into the drilling processes, affecting the accumulation of heat in the rivet and base metal contact area; riveting press-in speed is too fast, firstly the heat is not yet generated, rivet materials are bent. The smaller press-in distance and stop procedure speed may regulate the fastening effectiveness of the riveting-heading in the friction riveting processes.
    Effects of Fracture Criterion on TC4 Titanium Alloy Plates against Impacts of Ogival-nosed Projectiles
    DENG Yunfei;ZHANG Yong;ZHANG Weiqi;XU Meijian;WANG Lujun
    2019, 30(19):  2378-2384. 
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    In order to understand the impact resistance mechanics properties of TC4 titanium alloy, a one-stage light gas gun was used to launch the ogival-nosed projectiles on the plates of TC4 titanium alloy, while the impact velocity ranged from 125.9 m/s to240 m/s. The initial-residual velocities of projectiles and the failure mode of plates were obtained by impact test, and the ballistic limit velocity was obtained by fitting the initial-residual velocity of the projectiles with the formula. 3D models of projectile impact targets were established by using ABAQUS/Explicit finite element software. In order to study the effects of fracture criterions on the TC4 titanium alloy plates against the impacts of ogival-nosed projectiles, the different fracture criterions were used for numerical simulation, and the numerical prediction results were compared with the experimental ones. The results show that the predicted results of Hancock-Mackenzie(H-M)criterion are more close to the test ones from the comprehensive consideration of ballistic limit velocity and failure modes, which indicates that the numerical prediction results maybe improved by accurately considering the relationship between failure strain and stress triaxiality.
    Rolling Force Model of Large Conical Cylinders Considering Conical Metal Flow
    DONG Zhikui1,3;PENG Liwei1;JIAO Yunjing1;SUN Jianliang 1,2;ZHUO Chaoyue 1;ZHAO Jingyi1;LU Mingli 3;YANG Zhiming3;WANG Peiliang3
    2019, 30(19):  2385-2393. 
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    Considering the conical metal flow due to the conicity of large conical cylinders, the mechanical models of rolling force for large conical cylinders were established based on differential layered calculation method and slicing method ,and then the finite element models of the rolling processes for large conical cylinders were performed using the ABAQUS software. The results of model calculation and finite element simulation show that the relative errors of rolling forces between mechanics models and finite element models are less than 20%. The distribution of unit rolling force between model calculation and finite element simulation is compared and analyzed afterwards. Finally, the application scopes of the mechanics model established for stable rolling are obtained by analyzing the speed ratio of core roller to outer roller.