Papers by Author: Zhi Bo Dong

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Authors: Jia Jie Wang, Zhi Bo Dong, Jing Qiang Zhang, Jian Guo Yang, Xue Song Liu, Hong Yuan Fang, Tie Gang
Abstract: In this paper, cold bending properties of Q620-CF steel butt joints were analyzed based on the finite element method. Finite element analysis (FEA) results indicate that the flush under-matched butt joints have lower bending properties than the flush equal-matched butt joints, but under-matched butt joints with definite reinforcement shape can get greater bending force and better cold bending angles than the flush equal-matched butt joints. It shows that shape design of the reinforcement can improve the bending load-carrying capacity of under-matched joints. The reliability of the FEA has been verified by the experiment.
Authors: Jing Qiang Zhang, Jian Guo Yang, Jia Jie Wang, Xue Song Liu, Zhi Bo Dong, Tao Wang, Hong Yuan Fang
Abstract: Based on the estimation of the critical hydrogen pressure and concentrations required for hydrogen-induced delayed cracking in high-strength steel, the conclusion that welded joints are hydrogen pressure microcracks body can be drawn under certain conditions. Through the analysis of the relationship between the microstructure evolution of welded joints, diffusion enrichment of hydrogen and cracking behavior, the formation mechanism of hydrogen-induced delayed cracking in weld center of high-strength steel joints is analyzed and the mechanism that stress induced the residual diffusion hydrogen gathered to promote the hydrogen pressure microcracks propagation is proposed. The research shows that the initation and propogation of hydrogen-induced delayed cracking in weld center can be divided into two stages, i.e. irreversible hydrogen damage stage and reversible hydrogen damage stage. In irreversible stage hydrogen pressure is the main causes of the initation of microcracks, while in reversible stage welding residual stress and residual diffusible hydrogen are necessary conditions for microcracks growth. The microcracks growth can be controlled by regulating welding residual stress.
Authors: Jian Guo Yang, Wei Fu, Jia Shuang Gao, Xue Song Liu, Zhi Bo Dong, Hong Yuan Fang
Abstract: A new thinking was introduced that combine finite element analysis(FEA) for welding process simulation with virtual manufacture(VM), it is significant research according to comparison of FEA for welding process and VM, parameters input by FEA pre-processor and by VR technology, FEA results cab be shown by FEA post-processor and by VR technology. The framework for welding FEA based on VM was proposed and some key technologies were also discussed.
Authors: Yan Hong Wei, Yan Li Xu, Zhi Bo Dong, Ji Lin Xiao
Abstract: The stainless steel SUS316 grain growth process in heat affected zone (HAZ) of gas tungsten arc welding (GTAW) process is studied with Monte Carlo (MC) simulation. The heat transfer and fluid flow model provides the thermal history and thermal distribution of the weldments for MC grain growth simulation. The grain growth evolution is simulated both in isothermal and in HAZ environment. The simulating results show clearly the “thermal pinning” effect on the grain growth evolution in HAZ compared with the isothermal results.
Authors: Zhi Bo Dong, Yan Hong Wei, Wen Jian Zheng, Guang Xu Hu, Rui Ma
Abstract: TA15 airplane wall panels are used widely in aircraft manufacture, which consist of some reinforced ribs and a motherboard. Therefore, welding sequences of different reinforced ribs directly determine distortion and residual stress distributions of welding wall panels, and then affect the structure service performance. Therefore, it is important to get the optimistic sequence during manufacture processing of welding wall panels. This paper analyses and predicts regularities of distributions of residual distortion and stress under four kinds of different welding sequence namely, order welding sequence, head-tail welding, head-tail symmetry welding and center symmetry welding. Compared the distortion and residual stress of four kinds of sequences, it is obvious that the welding distortion is smaller and welding quality is better under head-tail symmetry welding sequence, and the order welding sequence is the worst. The simulated distortions are in good agreement with the experiments. So this study puts forward the best welding sequence when welding airplane wall panels, which adapt to any amounts of reinforced ribs welded with the motherboard.
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