A Critical Assessment of J-Integral and CTOD as Fracture Parameters

摘要

Elastic-Plastic Fracture Mechanics (EPFM) is often used for the integrity assessment of components made from ductile materials. It offers two fracture criterions viz., the J-integral and Crack Tip Opening Displacement (CTOD) which predicts the onset of unstable crack growth in ductile materials or materials undergoing significant plastic deformation. Hence the measurement of these parameters is vital. After presenting a brief introduction to the J-integral, CTOD and the relationship between these two parameters, the basic technique for measuring the J-integral for mode I problem through numerical simulation for is illustrated. The objective of this work is to critically assess the viability of the aforementioned fracture parameters in the integrity assessment of structures. A number of differences and similarities that exists between these two parameters in terms of quality and measurement methods as given in the standards (such as American Society for Testing and Materials and British Standards Institution) is brought out in this work. In addition, the misconceptions detained about the elastic-plastic fracture parameters is discussed.