Numerical characterization of anisotropic damage evolution in iron based materials

A damage plastic constitutive model for metals is proposed in this paper. An anisotropic damage tensor and a damage surface are adopted to describe the degradation of the mechanical properties of metals. The model is developed within the thermodynamic framework and creates an anisotropic damage plastic model with the ability to describe the plastic and damage behavior of iron based materials. According to the principle of strain energy equivalence between the undamaged and damaged materials, the linear elastic constitutive equations for the damaged material expressed a stiffness tensor in the damaged configuration. The damaged material is modeled using the constitutive laws of the undamaged material, in which the stresses in the undamaged configuration are replaced by the stresses in the damaged configuration. To simulate the onset of plastic deformation and damage, yield and damage surfaces are applied and, in accordance with the normality rule, evolution laws for the damage variables are achieved to complete the proposed damage plastic model. Implementation of the model in the form of a practical method, based on the forward Euler integration scheme (modified forward Euler integration with error control) is discussed. Finally, the constitutive response is compared with some experimental results and classical plasticity results for validating the capability of the proposed model. Good agreement between the experimental results and the model is obtained. (c) 2014 Sharif University of Technology. All rights reserved.