A Computational Model for the Finite Element Analysis of Thermoplasticity Coupled with Ductile Damage at Finite Strains

An updated Lagrangian implicit FEM model for the analysis of large thermo-mechanically coupled hyperelasticviscoplastic deformations of isotropic porous materials is considered. An appropriate framework for constitutive modelling is introduced that includes a stress-free thermally expanded con9guration and a plastically deformed unstressed damaged con9guration. A two-level iterative scheme is employed at each time increment to solve the 9eld equations governing the conservation of momentum (mechanical step) and the conservation of energy (thermal step) for the coupled thermo-mechanical problem. Exact linearizations for the calculation of the tangent sti=ness are performed in each of these solution steps. A fully implicit, thermo-mechanically coupled and incrementally objective Euler-backward radial return based map is developed for the time integration of the constitutive equations. The present model is used to analyse a number of benchmark examples including metal forming processes wherein temperature and the accumulated damage play an important role in in?uencing the deformation mechanism and the nature of the deformed workpiece. Copyright ? 1999 John Wiley & Sons, Ltd.