Nonlocal integral formulation for a plasticity-induced damage model

Abstract

Ductile failure prediction commonly involves the use of the finite element method within an elasto-plasticity framework coupled with damage. As strain localisation takes place, the partial differential equilibrium equation experiences a loss of ellipticity and the numerical result becomes mesh dependent. One possible approach is to regularise the solution by the introduction of an internal length, which is related to the microscopic structure of the material. In this context, nonlocal integral and gradient-enhanced formulations [2] are commonly employed as regularisation strategies. In this work, a finite element formulation based on a nonlocal integral implementation proposed by Strömberg & Ristinmaa [7] is extended for a simplified version of Lemaitres ductile damage model [1]. Since only the computation of the internal force is affected in this strategy, its implementation in existing FE codes is relatively straightforward. The results of a sample case show that the implemented strategy acts as localisation limiter.