Numerical Damage Modelling of Aluminium Alloys for Wide Range of Stress Triaxiality

Abstract

There have been many efforts to investigate and develop a mechanical plasticity, damage and failure models for metal alloys in the last couple of decades. These models (single and multi-damage parameters) are generally based on energy and constitutive equations to simulate the fracture and failure processes in metal alloys. The conventional fracture mechanics theory and its applications have been successfully employed to study fracture and failure processes. However, these methods have serious short comes in predicting the damage and failure in metal alloys where the fracture is dominated by the presence of defects like micro-voids (and their growth, nucleation and coalescence), oxides and inclusions. In the present study, following the in-depth study of damage initiation and progression in aluminium alloys, a frame work has been setup to develop a numerical model for damage accumulation. Based on the existing phenomenological damage theory, a mathematical basis for damage initiation and also damage accumulation under wide range of stress triaxiality (including near pure shear) has been developed. The damage model has been checked and verified using a result of experimental-simulation comparative study. The experiments have been carried out using samples made from squeezed and high pressure casting step plates. One of the main contributions of this paper is to show the advantages of using plasticity-based modified damage models to investigate the damage accumulation in cast aluminium alloys.