J-estimation for semi-elliptical surface cracks in wide plates under direct tension

Large marine structures can be subjected to extensive localized damage, with strains reaching 10 times the yield strain. Small defects might propagate, and accurate defect assessment is required for safe operation. To simulate this problem, J-integrals have been computed for semielliptical cracks in wide steel plates under tension. Three-dimensional (3D) elastic-plastic finite element analysis was used to model shallow crack geometries with 0.2 less than or equal to a/c less than or equal to 0.57 and 0.05 less than or equal to a/t less than or equal to 0.15. The material responses were linear elastic followed either by power hardening, or perfect plasticity and power hardening. it was found that, in contrast to previous studies on single edge notch geometries, the material law does not have a major influence on the J-strain behaviour. Results obtained from the 3D analyses form the basis for the development of a J-based estimation scheme.