Finite element modeling of clinch forming with automatic remeshing

The aim of this work is to propose a fast and efficient finite element method for studying clinch forming with respect to process parameters. The clinch process is a mechanical joining technique that has been studied for many years in the hope of achieving quality joints for dissimilar metal sheets with different surfaces and thickness. Its basic principle is to clamp together several metal sheets by an impact extrusion between a punch and a die. A dedicated finite element computer code is developed to specifically simulate this forming process. The resolution of the updated Lagrangian formulation is based on a static explicit approach. The integration of the elastic-plastic behavior law is realised with a Simo and Taylor algorithm. The contact conditions are insured by a penalty method. Furthermore, due to large mesh distortions, remeshing techniques are used in order to compute an accurate solution. After designing a new mesh, field variables are transferred by a diffuse approximation method. The results that we present are compared with experimental data and numerical results calculated with a static implicit method (ABAQUS). The influence of process parameters (tools geometry, friction, material behavior) is also shown to be accurately taken into account. (C) 2000 Elsevier Science Ltd. All rights reserved.