板材多点成形过程的有限元分析

多点成形过程采用静力隐式格式进行数值模拟是比较合适的。本文建立了用于多点成形过程分析的静力隐式弹塑性大变形有限元方法 ,给出了对稳定迭代收敛过程效果较好的板壳有限单元模型、处理多点不连续接触边界的接触单元方法以及增量变形过程中应力及塑性应变计算的多步回映计算方法。基于这些方法编制了计算软件 ,应用该软件进行了矩形板的液压胀形过程及球形模具拉伸成形过程的有限元分析 ,数值计算结果与典型的实验结果及计算结果吻合很好。最后给出了球形、圆柱形目标形状的实际多点成形过程的数值模拟结果。

Finite element analysis of the process of Multi-Point Forming for sheet metal

The process of Multi-Point Forming (MPF) should be simulated by finite element with static implicit scheme. In this paper, an elastic plastic large deformation finite element approach based on the static implicit scheme for the simulation of MPF process of sheet metal is described. The shell element model, the contact element technique to simulate the contact interface and the multi-step Radial return method for the calculation of stresses and strains in the process of plastic increment deformation are formulated. The present methods are effective to stabilize the iteration process of static implicit scheme. According to those methods, a finite element analysis code for the simulation of sheet metal forming process is developed. The numerical results calculated by the code for hydrostatic bulging of rectangular sheet and for a two dimensional stretching with a hemispherical punch coincide with the typical testing and calculating results. The numerical results for the springback analysis of sheet metal forming with MPF cylindrical die and the simulation of forming process of sheet metal with MPF spherical die are also given in the paper.