J Integral Evaluation of CT Specimen in Elastic-plastic State

Abstract

CT specimens are analyzed elastic-plastically by the three dimensional finite element method and the distribution of the three dimensional J integrals along the crack front is obtained. For 1CT specimens without side groove. the J value at the center of the specimen is the maximum and is the minimum near the surface. It is shown that the change in both values becomes smaller when introducing the curved crack front assuming the fatigue precrack. For the side grooved specimen. the experimental J value using the net thickness is better than that using the effective thickness. It is shown that the J value is nearly equal along the crack front for the 25 side grooved specimen. In every case, the J value obtained by the load versus displacement curve coincides well with the average J value over the specimen thickness.