HRR FIELDS FOR DAMAGED MATERIALS

The paper presents an investigation of the interaction between a macroscopic crack and distributed damage in an elastic-plastic material based on the HRR field model for virgin materials. This is achieved by describing the mechanical effects of the distributed micro-cracks in terms of the damage variable D on the HRR fields. Damage evolution equation and the constitutive equations coupled with damage are formulated and the resulting boundary value problems are solved numerically. Material constants mu, n and m0 are varied to examine their effects on the resulting stress distributions. It is found that the HRR fields for damaged and virgin materials are surprisingly similar although the severity of damage equivalent stress is of several orders of magnitude higher than the conventional plastic equivalent stress without damage consideration. Furthermore, it is shown theoretically and justified numerically that the J-integral loses its path independency for damaged materials, causing the amplitude of the singularity K(D) to remain an unknown variable in the asymptotic analysis.