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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.

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The ability to quantify the material damage at different length scales is critical in the multiscale analysis of material behavior from nanoscale to macroscale. In this article, on the basis of the equivalence of complementary elastic energy we propose a multiresolution rule that transforms different levels of material defects to the equivalent degradation of material properties. It facilitates a sequential memory-efficient processing of massive material defects in a multiresolution framework, and also supports a functionality of partial damage conversion to serve different needs in subsequent numerical analyses. Numerical simulation was conducted with different settings of material defects. The analysis results indicate the efficacy of the proposed method, offering a potential (i) to interface between multiscale material defects and (ii) as an effective method of homogenization for the determination of the damage variable in continuum damage mechanics.

This paper presents an alternative method of material damage evaluation based on the X-ray computer tomography-detected microdefects and multiscale computer simulation. This is achieved by developing a method of the digital diagnosis and full-field numerical calculation of material degradation in macroscopic material test specimens. The method comprised three basic components: (a) digital detection and processing of micro/mesoscale material defects of macroscopic material test specimens; (b) multilevel meshing and multilevel finite element analysis for evaluating local/global material degradation; and (c) synchronized experimental and numerical determination of material damage. The unique contributions of the proposed approach include (a) a multilevel finite element meshing and analysis scheme that makes the full-field estimation of material degradation in macroscopic test specimens computationally tractable on regular workstations, (b) full-field exploration of mesoscale material defects (i.e., those with a feature size from several micrometers to a few millimeters), which play a crucial role in failure analysis of engineering components, and (c) the proposed method offers a significantly better accuracy in estimating material degradation in terms of effective modulus than the conventional analytical models in continuum damage mechanics and micromechanics. Test results of aluminum alloys confirm the efficacy of our approach in the digital interrogation of material degradation.