Study on the Relationship Between J-Integral and COD
STUDY ON THE RELATIONSHIP BETWEEN J-INTEGRAL AND COD

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