3-DIMENSIONAL CELL MODEL ANALYSES OF VOID GROWTH IN DUCTILE MATERIALS

Three-dimensional micromechanical models were developed to study the d amage by void growth in ductile materials. Special emphasis is given t o the influence of the spatial arrangement of the voids. Therefore, pe riodical void arrays of cubic primitive, body centered cubic and hexag ona structure are investigated by analyzing representative unit cells. The isotropic behaviour of the matrix material is modelled using eith er v. Mises plasticity or the modified Gurson-Tvergaard constitutive l aw. The cell models are analyzed by the large strain finite element me thod under monotonic loading while keeping the stress triaxiality cons tant. The obtained mesoscopic deformation response and the void growth of the unit cells show a high dependence on the value of triaxiality. The spatial arrangement has only a weak influence on the deformation behaviour, whereas the type and onset of the plastic collapse behaviou r are strongly affected. The parameters of the Gurson-Tvergaard model can be calibrated to the cell model results even for large porosity, e mphasizing its usefulness and justifying its broad applicability.