Three dimensional finite element analysis on damage propagation and ductile fracture

Abstract

In this paper, the three dimensional finite element analysis of damage propagation and ductile fracture is performed by using the concept of Continuum Damage Mechanics. The isotropic damage model based on the generalized effective stress concept is used for representing the deterioration of ductile solids. In this model, the degree of stiffness degradation is considered as a measure of material damage and so fracture can be explained as the critical deterioration of stiffness at a material point. As computational procedures, the finite element approximation of largely deforming body based on the incremental total Lagragian concept is followed. To resolve the difficulties due to incompressibility and bending behaviors, an incompatible element is implemented by extending from the case of linear elasticity. The Heun's method along with backward Euler method and the variable time step algorithm are used for the integration of constitutive equation and a modified Riks' continuation technique is used as a solution procedure. As numerical examples, 3D compact specimen and the initially cracked specimen with an elliptical hole are studied. It can be concluded that the proposed damage model and the numerical schemes are reasonable and efficient to describe the damage propagation of ductile solids. Nomenclature