Numerical determination of parameterised failure curves for ductile structural materials

Abstract

Abstract Inhomogeneities such as voids or inclusions can lead to stress and strain concentrations under external loading conditions due to the different elastic – plastic and thermal properties of the phases. To describe the damage behavior of ductile materials, a damage parameter was introduced by Rice and Tracey and so-called failure curves (determined by experiments) describe different possible stress – strain states at fracture. The experimental effort can be reduced by applying unit cell models consisting of a single void in the base material with a pre-defined void volume fraction f0. With these models, stress triaxialities and plastic strains are calculated and failure curves are derived. Parameter studies are performed to obtain analytical equations for the material dependent constants A and B as a function of the initial void volume fraction f0 and the hardening exponent N as well as the yield stress 0.