The GTN damage model based on Hill’48 anisotropic yield criterion and its application in sheet metal forming

To predict the damage evolution of anisotropic plastic voided ductile materials, Gurson–Tvergaard–Needleman (GTN) yield criterion is developed based on Hill’s quadratic anisotropic yield criterion (1948) and isotropic hardening rule for matrix material. A user-defined subroutine is developed using the above model. An implicit stress integration procedure is modified to adapt the explicit dynamic solver. After performing a series of single element tests, cylindrical tension and thick plate tension are analyzed. Then a benchmark of NUMISHEET’2002, i.e. deep drawing of cylindrical cup, is taken as an example of sheet metal forming. Comparisons are made among the von Mises constitutive model, isotropic and anisotropic plastic GTN damage models. It is found that plastic anisotropy of the matrix in ductile sheet metal has influence on both deformation behavior and damage evolution of the material.