New Proposal of Crack Energy Density Concept as a Fundamental Fracture Mechanics Parameter

Crack energy density concept is newly proposed as one of the most important parameters in fracture mechanics, and the role of it is discussed. This parameter represents the state of the work absorbed (strain energy in case of the continuum) at crack tip per unit area of crack plane generally, and it should be called, as it were, strain energy area density especially for the case of the continuum. The introduction of the concept enables us to make a unified smooth description of the fracture condition from completely elastic (brittle) fracture to ductile fracture with large scale yielding, and also to solve some ambiguous problems in fracture mechanics. For example, the physical meanings of G0(K0) criteria ; Jc criteria and COD criteria on fracture are explained clearly through the concept.