ADAPTIVE RIGID-PLASTIC MESHLESS GALERKIN METHOD AND ITS APPLICATION IN ANALYSIS OF EXTRUSION PROCESSES  

作　　者：WU Xin ZHAO Guoqun WANG Weidong GUAN Yanjin LU Ping 

机构地区：[1]School of Mechanical Engineenng, Hangzhou Dianzi University, Hangzhou 310018, China [2]Engineering Research Center for Mould ＆ Die Technology, Shandong University, Jinan 250061, China [3]Engineenng Research Center for Mould ＆ Die Technology, Shandong University, Jinan 250061, China

出　　处：《Chinese Journal of Mechanical Engineering》2007年第2期26-31,共6页中国机械工程学报（英文版）

基　　金：This project is supported by National Natural Science Foundation for Dis-tiguished Young Scholars of China (No. 50425517).

摘　　要：Under the hypothesis of the rigid-plastic material, specific efforts are placed on the developments of the key simulation techniques of the meshless Galerkin method because of the complexity of the deformation process as well as the generality and atomization of the simulation procedures for non-steady state large deformation plastic processes, therefore, an adaptive rigid meshless Galerkin method is developed. The influence domain control method is used in the least square approximation by dynamic evaluation of the magnitude of the influence domain and the effective control of the amount and the positions of the points in the least square approximation in order to improve approximation precision. The amount of the Gauss integration points in the discrete domain is maintained in a considerable magnitude in order to ensure the integration precision in the discrete domain. The length of the frictional boundary of the plastic deformation process may be getting longer when its deforma- tion is getting severe. Thus, the densities of the boundary points of some places get lower. The adaptive boundary points setting method is employed to improve the approximation precision of the boundary points and enhance the constraint of the boundary condition by adaptive control of boundary point density. Some typical extrusion processes are analyzed, detail simulation results such as the deformation field, velocity field, effective strain field, effective strain rate field, the volume loss curve and load-stroke curve are obtained. The effectiveness of the method developed is demonstrated and the precision of the meshless simulation is proved by overall comparison with the results obtained by using the commercial software deform.Under the hypothesis of the rigid-plastic material, specific efforts are placed on the developments of the key simulation techniques of the meshless Galerkin method because of the complexity of the deformation process as well as the generality and atomization of the simulation procedures for non-steady state large deformation plastic processes, therefore, an adaptive rigid meshless Galerkin method is developed. The influence domain control method is used in the least square approximation by dynamic evaluation of the magnitude of the influence domain and the effective control of the amount and the positions of the points in the least square approximation in order to improve approximation precision. The amount of the Gauss integration points in the discrete domain is maintained in a considerable magnitude in order to ensure the integration precision in the discrete domain. The length of the frictional boundary of the plastic deformation process may be getting longer when its deforma- tion is getting severe. Thus, the densities of the boundary points of some places get lower. The adaptive boundary points setting method is employed to improve the approximation precision of the boundary points and enhance the constraint of the boundary condition by adaptive control of boundary point density. Some typical extrusion processes are analyzed, detail simulation results such as the deformation field, velocity field, effective strain field, effective strain rate field, the volume loss curve and load-stroke curve are obtained. The effectiveness of the method developed is demonstrated and the precision of the meshless simulation is proved by overall comparison with the results obtained by using the commercial software deform.

关 键 词：Rigid-plastic Galerkin Adaptive Non-steady state Extrusion Severe deformation 

分 类 号：TG371[金属学及工艺—金属压力加工]