Abstract: 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 J2 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.

Key words: Drawing, Finite element method, Numerical computation, Sheet metal