A finite element analysis of the bending and the bendability of metallic sheets

The main objective of this paper is to study the bendability of metallic sheets by using the finite element method. In this aim, two variants of an advanced Gurson-Tvergaard-Needleman model [1, 2] are implemented in the home made FE code LAGAMINE [3, 4] and coupled with the Thomason model to predict the coalescence of voids. This advanced model is an extension of the original one to take into account of the plastic anisotropy and the mixed (isotropic + kinematic) hardening of the matrix. The difference between the two variants is related to the modeling of the damage evolution. As the advanced model is used to study the bending process, its yield function is slightly modified in order to take into account the loadings with negative triaxiality ratios. These present implementations are used to simulate the pure bending process and to predict the bendability of dual phase (DP) steel. The combined effect of an initial geometrical imperfection and damage evolution on the bendability is also studied.