三维板料成形过程的有限元分析

基于有限变形理论建立了三维金属板料成形过程的弹塑性有限元数学模型。数学模型采用物质坐标系中的Total Lagrange描述、J 2型本构方程和等向强化假设，考虑了板料的厚向异性，对于金属板料与模具的摩擦定律。为简化计算采用薄膜单元。为了改善节点接触状态变化时计算的收敛性，提出了“弹性边界层”方法。采用根据此模型编制的程序模拟了机油收集器基本件的成形过程，并与试验结果进行了比较。

FINITE ELEMENT ANALYSIS OF THREE DIMENSIONAL SHEET METAL FORMING PROCESS

Based on the finite deformation theory and elastic-plastic membrane theory,a finite element (FE) model for simulating the three dimensional sheet metal forming p-rocess is developed. In the model, Total Lagrangian formulation in the current coordinate system and J_2 type incremental constitutive equation in an ordinary curvilinear coordinate system are adopted. Isotropic hardening and anisotropy in the normal direction of the sheet material are assumed. To improve the stability of numerical computation, the approximate coulomb friction law is used at the contacting surfaces between sheet metal and punch or die, and modified Newton iteration is adopted. A elatic boundary layer method is proposed to overcome numerical instability caused by the change of contact state of nodal points. Numerical results obtained from application of the FE program to the forming process of an oil collector are compared with experimental data.