Finite element simulation of multi-point sheet forming process based on implicit scheme

Multi-point forming (MPF) is a flexible manufacturing technique for three-dimensional sheet metal forming. The deformation of material and contact boundary in multi-point forming processes are very different from those in traditional stamping processes. In this paper, an incremental displacement approach on the basis of updated Lagrangian formulation and elastic–plastic material model for finite element simulation of MPF process is described. An effective algorithm for the integration of stresses is introduced. The multi-point, discontinuous contact interface between sheet and tools is modelled with contact finite element based on the penalty method and on the Coulomb non-classical friction law of elastic–plastic formalism. An integration algorithm of the frictional contact constitutive equations is derived. Forming processes of sheet metal are analyzed by using a new finite element code developed by the authors. The results of numerical examples show good general coincidence with those of the experiments and explicit/elastoplastic analysis reported in the literature. Two representative examples of application in MPF are also presented in order to show the applicability of the algorithm.