Finite Element Damage Analysis of Plate Bending

Abstract

A ductile material is capable of undergoing large plastic deformations. The accumulated plastic deformation can induce the changes of microstructures of the material through, for example, the nucleation, growth and coalescence of microvoids. These changes in material microstructures are the irreversible thermodynamic processes and result in a progressive degradation on the material properties. The process of the initiation and growth of microvoids and other microdefects induced by plastic deformations in ductile solids is called the ductile plastic damage. The primary interest of the ductile plastic damage is to study the influence of microvoids resulting from plastic deformations on the degradation of material properties. The changes on material properties can be studied by either a phenomenological damage model or a micromechanical damage model. A number of damage definitions and measures were proposed for both the models (vide the review papers of Krajcinovic, 1984, 1989; Chaboche, 1988; among others). Within the framework of phenomenological damage model, the damage of a material can be measured in macroscale by the deduction of mechanical properties, such as the elasticity constants (Lemaitre et al., 1979). Moreover, the changes of the macro-mechanical properties can be characterized by the damage effect parameters which are able to be determined from experiments (Lemaitre, 1985). These damage parameters are the internal state variables in thermodynamics.