MICROMECHANICAL MODELLING OF DAMAGE AND FRACTURE OF DUCTILE MATERIALS

A micromechanical model of ductile damage by void nucleation, growth and coalescence is widely and successfully applied to describe phenomena of ductile tearing. The model’s fundamental principles, and especially the constitutive equations of Gurson, Tvegaard and Needleman (GTN-model), are briefly described. Some of the material parameters of the GTN-model are calibrated by performing cell model calculations, which is a method of determining the structural behaviour of a single void in a plastic material. The approach is used to study the dependence of material strength and toughness on microstructural features of nodular cast iron. The numerical simulations were realized within the FE-program ABAQUS by a user-supplied material model.