Influence of computational parameters and nonlinear unloading behavior on springback simulation

Abstract

The advanced high-strength steels (AHSS) have become an interesting alternative to the automotive industry that aims to reduce the thickness of the components without compromising the structural performance and absorption capacity of impact. However, their mass utilization is still limited due to computational problems to predict the occurrence of the phenomenon of springback. Nonlinear unloading behavior following plastic deformation is identified as the factor that compromises the computational prediction of AHSS sheet forming. Moreover, it is observed sensitive dependence on correct choice of numerical parameters on the quality of the springback prediction such as the number of through-thickness integration points (NIP), coefficient of friction, the number of element on tool radius and simulation punch velocity. The aim of this study is to evaluate the degradation of elastic modulus and how the choice of numerical parameters can affect the computational prediction of AHSS springback. For this purpose, a user subroutine has been implemented in ABAQUS to describe the degradation of the modulus of elasticity during unloading, and several numerical parameters have been evaluated. It was possible to observe the influence of considering the degradation of elastic modulus during simulation and the large or small influence of some computational parameters.