盒形件成形过程的计算机模拟

本文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薄膜有限元数学模型.数学模型采用流动坐标系中的Total Lagrange描述、J_2型本构方程、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采用近似的库仑摩擦定律.采用根据此模型编制的程序模拟了盒形件的成形过程,并与实验结果进行了对比.

Computer Modelling for the Forming Process of Boxlike Parts

Based on the finite deformation theory and elastic-plastic membrane theory, a finite element (FE) model for simulating the three dimensional sheet metal forming process has been developed. In the model, Total La-grangian formulation in the current coordinate system and J2 type incremental constitutive equation in an ordinary curvilinear coordinate system have been 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 con tacting surfaces between metal sheet and punch or die, and modified Newton iteration is adopted. Numerical results obtained from application of the FE program to the forming process of boxlike parts are compared with experimental data. The computation results indicate that the membrane model FE program provides a simpler method for the analysis of three dimensional sheet metal forming and is suitable for those cases where the fillet radius or die gap is large.