STUDY ON THE RELATIONSHIP BETWEEN J-INTEGRAL AND COD

J-integral arid crack opening displacement 8 （COD） were important parameters for characterization of fractures in engineering materials. The relationship between J-integral arid COD has been investigated for a long time and was generally represented as J = m σy, δ, where σy is the yield strength arid m is a function of specimen geometry arid material properties. To determine the value of m, extensive studies and experiments have been performed. The method that used the fracture-surface topography analysis （ FRASTA ） for determining J-integral from fracture surfaces of materials was introduced. On the basis of the relationship between COD arid fracture surface average profile, the relationship between J-integral arid COD was deduced arid compared with the generally used equation. The method was experimentally confirmed to be able to provide a new way to determine the relationship between J-integral and COD.