Stress-state dependent phase-field modeling of ductile fracture using an enhanced adaptive meshless approach

Abstract

This paper presents enhanced phase-field techniques that improve the failure analysis of elastic–plastic materials. Previous studies have employed constant energy thresholds to avoid premature failure. However, this criterion ignores the dependence of ductile fracture behavior on various loading conditions and stress states. This study introduces a crack propagation energy criterion that is based on the stress state, considering the key contributions of stress triaxiality and the Lode parameter to ductile failure. To optimize computational performance and minimize the constraints on mesh size, a meshless procedure based on the radial point interpolation method and the background decomposition integration technique is utilized for the numerical analysis of ductile fracture. In the proposed meshless method, a novel adaptive node refinement strategy, based on the Delaunay triangulation method is employed. Some numerical example problems are solved to highlight the ability of the proposed adaptive model in effectively and precisely replicating intricate ductile fracture behaviors, such as plastic localization, and the initiation, growth, and coalescence of cracks.