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Table of Content

    28 September 2019, Volume 53 Issue 9 Previous Issue    Next Issue
    Hyper-Viscoelastic Model and Rate-Dependence in Large Strain Regime of Epoxy Shape Memory Polymer
    FAN Pengxuan,CHEN Wujun,HU Jianhui,ZHAO Bing,FANG Guangqiang,CAO Zhengli,PENG Fujun
    2019, 53 (9):  1017-1022.  doi: 10.16183/j.cnki.jsjtu.2019.09.001
    Abstract ( 1021 )   PDF (773KB) ( 334 )   Save
    In order to investigate the stress softening-stiffening effect and the rate-dependent properties caused by the hyper-viscoelasticity of epoxy shape memory polymer (ESMP) in large strain regime, this work makes attempt to reveal the softening and stiffening effect of ESMP near and above glass transition temperature (Tg). Firstly, to account the stiffening effect in large strain, a hyper-viscoelastic model is established by substituting the second-order polynomial hyper-elastic model to the linear Hooke’s law in generalized Maxwell model. Meanwhile, the material constants calibration equations which are convenient for engineering application are derived for the case of constant true strain rate in analytical form. Then, the tensile tests in various strain rates are carried out at temperature above Tg in rubbery state and 7℃ blow Tg, where the exponential tensile displacement curve are approached by finite pieces of linear displacement curve. The material constants are calibrated by the tests respectively. The numerical simulation of each test is carried out using the corresponding parameters, where the simulation results are found to have high consistency with the test results. The results indicate that ESMP behaviors significant rate-dependence. Meanwhile, the softening effect and the stiffening effect increase with increasing strain rate; the tangential modulus in a large strain rate is always greater than the tangential modulus in a small strain rate.
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    Bragg Reflection of Water Waves by Multiple Semicircular Structures Fixed on the Water Surface
    DING Weiwei,ZOU Zaojian,WU Jingping
    2019, 53 (9):  1023-1029.  doi: 10.16183/j.cnki.jsjtu.2019.09.002
    Abstract ( 1142 )   PDF (884KB) ( 260 )   Save
    Bragg reflection of water waves by multiple semicircular structures fixed on the water surface is investigated by using the boundary element method (BEM). It is based on the linear wave theory. In order to verify the correctness of BEM, the reflection coefficient of multiple semicircular structures fixed on the seabed is calculated. And the numerical results are compared with the theoretical results in literature. The effectiveness of the multiple semicircular structures fixed on the water surface in attenuating waves based on the principle of Bragg reflection is also proved. The effects of the number, the radius and the spacing of semicircular structures on the characteristics of Bragg reflection are investigated. The results of this study can provide a certain reference for the design of breakwater based on the principle of Bragg reflection.
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    The Compressible Effect on Characteristics and Translate Velocity of Vortex Ring
    LIN Haiyan,XIANG Yang,ZHANG Bin,LIU Hong
    2019, 53 (9):  1030-1039.  doi: 10.16183/j.cnki.jsjtu.2019.09.003
    Abstract ( 1152 )   PDF (8332KB) ( 294 )   Save
    Vortex ring is the fundamental structure in three dimensional fluid field. Three dimensional Navier-Stokes simulations are performed through finite volume method to reveal the compressible effect on axial symmetry vortex ring generated at the open end of a shock tube. Local Mach number and vortex Mach number can characterize the compressibility quantificationally. Compressibility vortex ring can be classified into three categories which correspond to subsonic, transonic and supersonic. The parameters related to vortex ring structure are also affected by compressibility. As the increase of compressibility, the vorticity profile in vortex core deviates from Gaussian distribution and the concentrated vorticity fields in the vortex core diminishes; the radius of vortex ring increase with the increasing compressibility; the radius of vortex core increase first then decrease slightly due to the embedded shock wave. The velocity of vortex ring is proportional to the compressibility. The theoretical velocity obtained from simulation agrees well with the calculated value obtained by vortex Mach number, which indicates that the formula is suitable to all three kinds of compressible vortex rings.
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    An Architectural Grid Generation over Free-Form Surfaces Based on Guide Curve Offsetting
    WANG Qisheng,GAO Boqing,WU Hui
    2019, 53 (9):  1040-1044.  doi: 10.16183/j.cnki.jsjtu.2019.09.004
    Abstract ( 916 )   PDF (4545KB) ( 281 )   Save
    With the advent of architectural CAD applications, architects and designers could model almost any curved surface geometry imaginable, whereas it is not an obvious task for engineers to efficiently create a grid structure on a complex surface that meets the architectural requirements. To generate regular and fluent grids over free-form surfaces, a grid generation method is presented based offsetting the guide curve on the surface directly, called spatial guide curve method. Firstly, one or two curves were defined as guide curves on the surface. Secondly, reference points were decorated on the guide curve with reasonable spacings, and then were offset and fitted into an offset curve on the surface extended properly. Thirdly, taking the newly generated offset curve as the guide curve, new offset curves were generated iteratively, and thus a set of offset curves were arranged. Finally, taking the offset curves as grid lines, the final grid was generated by doing operations on offset curves, like segmenting, connecting, trimming, etc. The grid trend was controlled by the guide curve. The grid size was controlled by offset distances of reference points and the grid shape was optimized by merging offset points which were too close. Cases studies were provided to illustrate the successful execution of these procedures. The results show that the grids generated by this method have advantages of regular shapes, fluent lines and desired trend, thereby satisfying aesthetic requirements.
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    Design and Optimization of Wireless Energy Supply System for Artificial Anal Sphincter
    WU Changjian,JIANG Zhihua,YAN Guozheng,ZHOU Zerun,WANG Zhiwu,ZHAO Kai,HAN Ding,JIANG Pingping
    2019, 53 (9):  1045-1050.  doi: 10.16183/j.cnki.jsjtu.2019.09.005
    Abstract ( 1074 )   PDF (3806KB) ( 271 )   Save
    Based on the principle of electromagnetic coupling, a set of wireless energy supply system was designed for the artificial anal sphincter system. The system contains five parts: wireless energy transmitter, wireless energy receiver, rectifier module, regulator module and charging module. This work focuses on the effect of transmitter launch angle frequency (40-120kHz) on the transmission power. We compare the charging effect and optimize the regulator module to meet the executing agency operating power requirements. The experiment results show that the transmission efficiency improves with the increase of the transmission frequency in a certain frequency range. When the transmission frequency is 120kHz, the transmission efficiency can reach 57.47%, the receiving power is 1.12W, and the lithium battery can be quickly charged, providing stable energy for the artificial anal sphincter system.
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    Characteristics of Power Lithium-Ion Batteries at Extreme Cold Environment
    HUANG Deyang,CHEN Ziqiang,ZHOU Shiyao,LIU Jian,ZHENG Changwen,GE Yunlong
    2019, 53 (9):  1051-1057.  doi: 10.16183/j.cnki.jsjtu.2019.09.006
    Abstract ( 1266 )   PDF (4405KB) ( 707 )   Save
    Research on characteristics of power Li-ion batteries at extreme cold environment is the most necessary task for optimizing the battery design and the battery management system of unmanned aerial vehicle powered by Li-ion batteries in the application of polar research. A series of experiments are taken to explore the characteristics of a 12 A·h Li(NiCoMn)O2 lithium battery at extreme cold environment. The results show that the available capacities of battery under different discharge rates decrease rapidly at subzero temperatures, and the attenuation rate of the maximum depth of discharge speed up with falling temperature. Meanwhile, the discharge internal resistances, especially the polarization resistance, increase substantially. The open-circuit voltage is reduced evidently. Moreover, the implement of preheating before discharging can well recover battery performance at the ambient temperatures below -40 ℃. The equilibrium temperature of battery surface remains unchanged under the same discharge rate even with changing preheating temperature. The capacity and power characteristics of battery can be recovered effectively by utilizing both the preheating and heat insulation methods at the same time.
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    Remaining Useful Life Prediction for Lithium-Ion Batteries Based on Time Interval of Equal Charging Voltage Difference
    LIU Jian,CHEN Ziqiang,HUANG Deyang,ZHENG Changwen,ZHOU Shiyao,JIANG Yu
    2019, 53 (9):  1058-1065.  doi: 10.16183/j.cnki.jsjtu.2019.09.007
    Abstract ( 1417 )   PDF (1446KB) ( 495 )   Save
    In order to solve the difficulty in measuring capacity directly and capacity regeneration during online remaining useful life (RUL) prediction for lithium-ion batteries, a new method is proposed based on time interval of equal charging voltage difference and optimized Gaussian process regression (GPR) model. Firstly, the GPR model with uncertainty expression is established and optimized by using combined kernel functions and particle swarm optimization. The time interval of equal charging voltage difference is extracted during the constant current charging process of lithium-ion batteries. The relationship between the time interval of equal charging voltage difference and capacity is analyzed by a generalized linear regression model. The time interval of equal charging voltage difference can act as a health indicator for RUL prediction of lithium-ion batteries. According to the data sets of charge/discharge tests of lithium-ion batteries, the verification experiments are carried out. The results show that the proposed method can predict nonlinear degradation of capacity well and have high prediction accuracy and online RUL prediction ability for lithium-ion batteries.
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    The Refined Simulation and Model Analysis of the Suspension Cable Guyed Tower
    NIE Xiaochun,YAN Zhitao,SHI Jinghua,YOU Yi
    2019, 53 (9):  1066-1073.  doi: 10.16183/j.cnki.jsjtu.2019.09.008
    Abstract ( 993 )   PDF (5395KB) ( 357 )   Save
    Based on the finite element software ANSYS, a beam element model and a refined shell element model of the suspension cable guyed tower was established. The variation of the strain of the members with the loading level are calculated by the above-mentioned two finite element models, and the calculation results of the two models are compared with the full-scale test results. At the same time, the influence of the above-mentioned two models on the overall response of the structure are also compared. The results show that the calculation results of the refined shell element model on the strain of the main and oblique members are in good agreement with the full-scale test results. The calculation results of the beam element model on the strain of the main members also agree well with the full-scale test results. However, there is a relatively large calculation error of oblique members’ strain in beam element model. The above-mentioned two finite element models have little effect on the overall response of the suspension cable guyed tower, but the effect on internal force of the members is relatively large.
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    Three-Dimensional Reconstruction Method for Small Scale Magnetic Target Based on Shape Inversion
    YIN Gang,ZHANG Lin
    2019, 53 (9):  1074-1083.  doi: 10.16183/j.cnki.jsjtu.2019.09.009
    Abstract ( 980 )   PDF (3451KB) ( 256 )   Save
    Three-dimensional reconstruction method for small scale magnetic target based on shape inversion is studied in this paper. Firstly, the magnetic gradient tensor data is used to estimate the approximate horizontal boundary, vertical boundary and magnetization direction. On this basis, the range of inversion space is selected, the inversion space is gridded, the initial inversion model and the module sets to be increased are given. Then, based on the established module selection function, the optimal growth module is selected in the module sets to be increased, and the inversion model of magnetic target and the module sets to be increased are updated iteratively until the threshold of the iterative objective function is achieved. Finally, the inversion model is the three-dimensional reconstruction results of small scale magnetic target. Simulation result shows that the three-dimensional reconstruction results have high similarity with the real target, and it can be used in the identification applications of magnetic targets.
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    Depth Composite Control of Low Speed Underwater Vehicle Near Surface
    ZHUANG Peng,FENG Zhengping,BI Anyuan,ZHENG Tianhai,PAN Wanjun,ZHAO Shuo
    2019, 53 (9):  1084-1090.  doi: 10.16183/j.cnki.jsjtu.2019.09.010
    Abstract ( 942 )   PDF (1122KB) ( 294 )   Save
    Due to low effectiveness of both bow and stern planes at low speeds, the near-surface suction force experienced by an underwater vehicle can hardly be counteracted by lifting forces generated by the control surfaces. To improve the performance of depth control system, therefore, a variable water ballast mechanism is introduced and thus leads to an over-actuated characteristic. A composite control scheme is proposed for such an over-actuated control system. The input of the feedforward controller is the disturbance force, which is estimated by the disturbance observer, and the output of the feedforward controller is the mass of ballast water. Besides, the input of the feedback controller is the depth error and the output of the controller is the deflection angle of control surfaces. The results of underwater tests show that the disturbance observer can accurately estimate the unbalanced force on the underwater vehicle, and the self-propelled water tank tests also show that depth control system of underwater vehicle based on composite control strategy has good control performance.
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    Dot-Track Association Algorithm for Radar Electronic Support Measurement Systems Based on Support Vector Machine
    WANG Jiangzhuo,XU Wencong,LI Jianxun,HE Fengshou,CAO Lanying,MIAO Lifeng
    2019, 53 (9):  1091-1099.  doi: 10.16183/j.cnki.jsjtu.2019.09.011
    Abstract ( 1220 )   PDF (1436KB) ( 385 )   Save
    Probabilistic data association is an important issue in multi-source information fusion algorithms. The data association problem based on radar and electronic support measurement (ESM) sensors is mainly discussed in this paper. As the azimuthal data of radar and ESM sensors have approximately the same distribution, the discriminant function can be obtained through the analysis of ESM data, and the corresponding decision rules can be used to associate the dots and tracks. The association issue can be essentially regarded as a pattern recognition problem. In this paper, considering the good performance of support vector machine(SVM) in pattern classification, we establish a dotting and tracking association model for radar ESM systems based on SVM algorithm. We train the SVM model with ESM data, and classify the radar data to acquire association result. Finally, the simulation results show that the association accuracy can be effectively improved compared with the classical multiple hypothesis tracking algorithm.
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    Explicit Asynchronous Time Steps Parallel Computational Method for Structural Dynamics Based on Multiple Overlapping Nodes
    MA Zhiqiang,LOU Yunfeng,LI Junjie,JIN Xianlong
    2019, 53 (9):  1100-1106.  doi: 10.16183/j.cnki.jsjtu.2019.09.012
    Abstract ( 997 )   PDF (1034KB) ( 325 )   Save
    The local refined mesh leads to a large increase of calculation time in the structural dynamic finite element analysis. In order to improve the calculation efficiency, an explicit asynchronous parallel computational method based on multiple overlapping nodes is proposed. The procedure combines domain decomposition with subcycling method. The whole structure is divided into several subdomains by node partition method and the integral step size is selected according to the internal mesh sizes of the subdomain. An explicit Newmark time integral scheme is adopted in the subdomain. Multiple overlapping nodes between different subdomains constitute the coupling region without the interpolation process in the subcycling process. Simulation results of two cases implemented on Tianhe 2 supercomputer platform show that the proposed method can improve the computational efficiency with a high computational accuracy.
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    Integrating Strategy of Preventive Maintenance and Buffer Allocation Considering Dynamic Degradations for Manufacturing Systems
    GUO Wenyu,ZHANG Xiufang,XIU Yujiao,XIA Tangbin,PAN Ershun
    2019, 53 (9):  1107-1114.  doi: 10.16183/j.cnki.jsjtu.2019.09.013
    Abstract ( 785 )   PDF (1018KB) ( 260 )   Save
    The article introduces a processing capability index combined with reliability into describing dynamic degradation of a two-machine-one-buffer system, and studies a joint optimization method of preventive maintenance and buffer allocation. Considering the production states and operation characteristics of manufacturing system, we establish a multi-stage dynamic model to illustrate the buffer fluctuation, and discuss the corresponding buffer cost and shortage cost models comprehensively. The minimum total average cost is used to develop the optimal joint policy of preventive maintenance and buffer allocation. A numerical case is used to prove the effectiveness of the proposed policy and the results have demonstrated the significant effect of buffer allocation on cost saving.
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    Influence of Blanking Process on the Magnetic Properties of Non-Oriented Electrical Steel Lamination
    WANG Xinke,WANG Zhe,CUI Ronggao,LI Shuhui
    2019, 53 (9):  1115-1121.  doi: 10.16183/j.cnki.jsjtu.2019.09.014
    Abstract ( 1065 )   PDF (5730KB) ( 354 )   Save
    In order to study the influence of blanking process on the magnetic properties of non-oriented electrical steel lamination, different shapes of punch and different blanking clearances are adopted. The relationship between the magnetic property deterioration and residual stress distribution of non-oriented electrical steel is studied. The results show that the blanking performance of the flat punch is the best, and the concave punch is better than the beveled one. In the considered blanking clearance range (5%~20% of sheet thickness), the magnetic property deterioration of the non-oriented electrical steel lamination decreases at first and then increases with the increasing blanking clearance. There exists an optimal clearance for reducing the magnetic properties deterioration. The magnetic property deterioration of non-oriented electrical steel lamination is mainly related to the peak residual stress. The larger the peak residual stress is, the worse the magnetic properties are. The study can provide parameter optimization guidance for blanking process of non-oriented electrical steel in industry.
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    Mechanical Properties of Three-Sheet Resistance Spot Welded Joints Under Different Lapping Orders
    ZHU Qiang,QIN Fei,WANG Wurong,WEI Xicheng
    2019, 53 (9):  1122-1129.  doi: 10.16183/j.cnki.jsjtu.2019.09.015
    Abstract ( 1325 )   PDF (7354KB) ( 245 )   Save
    Front wall beams and the support of A-Pillar are usually hot-stamped parts in side impact of vehicle, and front panel is made of mild steel with excellent formability by stamping, hence the area has formed a typical three-sheet resistance spot welded joints of unequal thickness and strength. In order to improve the overall load bearing capacity of spot welding joints, the paper investigates the influence of different lapping orders on overall mechanical properties of welded joints. Based on three kinds of material with unequal thickness and strength, B1500HS-1.4mm, B1500HS-1.6mm and DC06-0.8mm, the mechanical properties of different interfaces of two welded joints (strong-strong-soft and strong-soft-strong) under different lapping orders were compared. The nugget forming process, microstructure of nugget, fusion zone size and microhardness were also studied and analyzed. By investigating microstructure formation of nugget process of welded joints under different lapping orders, this paper reveals that the joint of strong-soft-strong can increase the bearing capacity. Finally, the article gives a reasonable design of strong-soft-strong lap joint in side impact of A-pillar and improves overall crashworthiness of vehicle.
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    Effect of Welding Energy on the Performance of Aluminum-Nickel Ultrasonic Welding Joints
    ZHANG Wei,AO Sansan, LUO Zhen,HAO Zhizhuang,CHEN Yao,FENG Mengnan,XIE Yan
    2019, 53 (9):  1130-1135.  doi: 10.16183/j.cnki.jsjtu.2019.09.016
    Abstract ( 1230 )   PDF (20790KB) ( 653 )   Save
    Aluminum-nickel is an important electrode material which has good application prospects to study the bonding mechanism and optimization technology of the joints. Ultrasonic welding of dissimilar metals, 1A99 aluminum alloy and N4 nickel alloy, were conducted in this research. The effect of welding energy on mechanical properties, macro morphology, atomic diffusion and fracture mode of the welded joints have been analyzed emphatically. The results show that under the high-frquency ultrasonic vibration, a sound aluminum to nickel ultrasonic welding joint is successfully obtained. The maximum tensile shear load of joint can reach 1121N at the welding energy of 600J. The hardness profile of aluminum side which is close to the sonotrode tip is decreased, while the hardness of nickel side is slightly increased during the welding process. By increasing the welding energy, the indentation depth on aluminum side is increased, and significant deformation of joints in the thickness direction is observed when the energy reaches 700J. The scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) analysis show that a 5.29μm thick transition layer in the faying interface between Al and Ni is found under the optimized welding parameters. And there is no intermetallic compound (IMC) formed in the joint. The brittleness problem of Al-Ni dissimilar metal joints caused by traditional fusion welding methods is solved in this study, which lays a theoretical foundation for promoting the development of Al-Ni electrode materials.
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    High-Temperature Friction of Uncoated 22MnB5 Boron Steel in Hot Stamping
    GAO Kaixiang,WANG Wurong,WEI Xicheng,MENG Hua
    2019, 53 (9):  1136-1142.  doi: 10.16183/j.cnki.jsjtu.2019.09.017
    Abstract ( 1025 )   PDF (3763KB) ( 256 )   Save
    The self-developed high-temperature friction tester was used to simulate the high-temperature friction process of uncoated 22MnB5 steel under actual hot stamping process. The influence of initial friction temperature, sliding speed and normal load on the friction behavior were analyzed. The results indicated that since the oxide layers formed on the surface of the specimen during transfer process had the same protective and lubricating effect on friction, the initial friction temperature had little effect on the friction coefficient. When the sliding speed was low, the oxides on the specimen surface would form small accumulation blocks with non-uniform thickness, which made the specimen surface uneven. And the oxides could not support the friction interface well, resulted in high coefficient of friction. As the normal load increased, the friction coefficient increased due to the spalling of the oxide layers and the exposure of the metal substrate.
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