CRACK OPENING DISPLACEMENT (COD) AS A FRACTURE PARAMETER AND A COMPARATIVE ASSESSMENT OF THE COD AND J-INTEGRAL CONCEPTS.

The crack opening displacement (COD) was proposed very early in the development of fracture mechanics as a parameter to assess the fracture resistance of structures. This paper discuses the COD concept, reviews its application to crack initiation and growth predictions in the elastic-plastic regime, and presents a parallel assessment of the COD and J-integral. Although the two concepts have been shown to be equivalent under certain conditions, the authors believe that the differences in their physical interpretations, in their theoretical foundation, and in their range of applicability in fracture mechanics need to be emphasized.