Prediction of Forming Limits Based on a Coupled Approach Between Anisotropic Damage and Necking Models

Abstract

This article presents an integrated approach for localized necking and failure prediction in sheet metal forming processes, based on the coupling between the anisotropic damage evolution law proposed by Lemaitre [1] and the modified maximum force criterion (MMFC) proposed by Hora et al [2]. To illustrate the essential features of the coupled approach, an aluminum alloy has been selected and numerical predictions have been compared with experimental forming limits, obtained for both linear strain paths evolutions. Numerical results show that the introduction of the softening behavior, caused by the increase of damage, into the necking criterion can play a significant role in triggering local necking, providing an improved prediction of the necking occurrence together with the capability of performing calculations of limit strains when they are governed by fracture rather than by local necking.