The effect of non-crack component on critical fracture energy of ductile material

Recently, Marie and Chapuliot have described ductile failure in terms of fracture energy which is associated with the local plasticity surrounding the crack tip. They introduced critical fracture energy, Gfr, as a new energy release term related to crack growth and also claimed that Gfr is a material property. They also proposed several schemes for the determination of the value of Gfr from specimens as well as from components. In all these methods the role of non-crack displacement in the crack growth process has not been considered. For the specimens or the components for which non-crack displacements are significant the proposed methods have some limitations in their application. In this paper an attempt has been taken to model the ductile crack growth phenomenon with the same approach of Gfr considering the effect of non-crack displacement during crack growth. The necessary modifications in a graphical method for determination of Gfr have been suggested. The expression for Ernest's JM-pl from which Gfr is calculated is also modified. The values of Gfr have been determined using the modified schemes for CT specimens and pipes with circumferential cracks and checked for whether Gfr is an intrinsic material property