Nonlocal Damage Gradient Model for Fracture Characterization of Aluminum Alloy

This article presents the development of a generalized nonlocal damage-coupled material model. The model introduces the concept of cumulative damage gradient through a set of damage evolution equations within the irreversible thermodynamics framework. The conventional damage-coupled plasticity models require either self-developed finite element codes or the mandatory use of regular elements. The proposed material model is implemented in a commercial finite element code ABAQUS (Version 6.5) via its UMAT subroutine. The implementation of this model on ABAQUS is described with a focus on the nonlocal treatment together with the derivation of the consistent tangent modulus (Jacobian). As a numerical example, the nonlocal damage model is applied to center-cracked specimen made of aluminum alloy 2024-T3. Comparison is made between the computed results and experimental ones. The validity of the proposed model is examined, and its effectiveness for engineering application is elucidated.