Numerical modelling of cyclic plasticity and fatigue damage in cold-forging tools

Industrial cold-forging tools with complex geometry are very likely to be e xposed to local plastic deformation near stress concentrating details. The accumulation of plastic deformation resulting from the cyclic loading condi tions leads to fatigue damage and eventually to generation of a crack in th e surface of the die. To study the effect of die prestressing on fatigue da mage development, a plane strain finite element model of a cold-forging die is analysed. A complex material model, combining kinematic and isotropic h ardening with continuum damage mechanics, is used to simulate the elastic-p lastic material behaviour and damage development. Furthermore, a range of u ncoupled damage measures are applied in the comparison of conventional and new prestressing concepts. (C) 2000 Elsevier Science Ltd. All rights reserv ed.