Papers by Author: Zheng Zhang

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Authors: Zheng Zhang, Geng Liu, Tian Xiang Liu
Abstract: An adaptive meshless element-free Galerkin-finite element (EFG-FE) coupling model for thermal elasto-plastic contact problems is developed to investigate the influences of the steady-state frictional heating on the contact performance of two contacting bodies. The thermal elasto-plastic contact problems using the initial stiffness method is presented. The local adaptive refinement strategy and the strain energy gradient-based error estimation for EFG-FE coupling method are combined. The adaptive meshless model takes into account the temperature variation, micro plastic flow, and the coupled thermo-elasto-plastic behavior of the materials, considering the strain-hardening property of the materials and temperature-dependent yield strength. The adaptive model is verified through the contact analysis of a cylinder with an elasto-plastic plane. The thermal effects on the contact pressure, stresses distributions with certain frictional heat inputs are studied. The results show that the accuracy of the solutions from the adaptive refinement model is satisfactory but the cost of the CPU time is much less than that for the uniform refinement calculation.
Authors: Dao Wu Shuang Shi, Wei Wang, Zheng Zhang, Xing Quan Liu
Abstract: Li3V2(PO4)3/C composite cathode material was prepared by carbothermal reduction using LiOHH2O, NH4H2PO4, NH4VO3 as raw material, sucrose as a coated carbon source, respectively. The electrochemical properties of Li3V2(PO4)3/C composite material prepared at different sintering temperature between 750°C and 900°C were investigated. The results demonstrated that by adjusting the sintering temperature, the electrochemical performance of the Li3V2(PO4)3/C material tends to be excellent, and when the temperature reaches 750°C, the Li3V2(PO4)3/C composite cathode material with the best electrochemical properties can be obtained.
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