Disturbed State Modelling of Materials and Interfaces, and Computer Implementation

Abstract

The disturbed state concept (DSC) provides a unified constitutive modelling approach for the characterization of materials and interfaces subjected to mechanical and environmental loading. It is based on the idea that during deformation, a material element experiences internal microstructural changes that transforms the initial relative intact (RI) material to fully adjusted (FA) or critical state (c), and as a result, the material is a mixture of randomly disturbed clusters of RI and FA states, Fig. 1. The DSC allows, in a hierarchical manner, development of specialized constitutive models to account for factors such as elastic, plastic and creep strains, hardening, microcracking, damage and softening, stiffening and cyclic fatigue failure. Details of the derivations of incremental equations for observed stresses and strains, definitions of RI and FA states and the disturbance function, validations with respect to laboratory tests for materials such as clays, sands, ceramics and solders, and validation using finite element procedures are given in [1–5]. Brief details are presented below.