On some fundamental concepts of Continuum Damage Mechanics Original Research Article

McClintock, Rice and Tracey conducted the pioneering studies on the growth of cavities. It is a well understood and accepted fact that theories of inelastic material behaviour have benefited greatly during the last two decades as a result of their being studied in the frame work of internal variables theories. Continuum Damage Mechanics (CDM) falls within the group of inelastic materials, and deals with materials that undergo structural weakening as a result of microcrack formation (brittle damage) or of void growth and coalescence (ductile damage) (cf. Reddy, 1988). There have been non-exhaustive lists of the theory of materials undergoing a progressive deterioration or degradation that is commonly experienced by mechanical properties of materials prior to the initiation of microcracks. Most of these theories are developed within the internal variable framework (cf. Reddy, 1988). The paper presents the concepts of plastic relaxation, the alternative formulation of the function Y(D), the force associated with the damage variable and a model for ductile plastic evolution. The proposed model is compared with the existing and standard model.