Papers by Author: Chang Sik Oh

Abstract: This paper quantifies the effects of geometry, the loading mode and the specimen size on fracture toughness of the API X65 steel, via plane strain finite element (FE) damage analyses using the GTN model. The validity of FE damage analyses is checked first by comparing with experimental test data for small-sized, cracked bar test. Then the analyses are extended to investigate the effects of the relative crack depth and the specimen size on fracture toughness. It is shown that fracture toughness of the API X65 steel increases with decreasing the relative crack depth and increasing the specimen size.

Abstract: This paper presents limit loads for circumferential cracked pipe bends under in-plane bending, based on detailed three-dimensional finite element limit analyses. FE analyses are performed based on elastic-perfectly-plastic materials and the geometrically linear assumption. Both through-wall cracks and part-through surface cracks (having constant depths) are considered, together with different crack locations (extrados and intrados). Based on the FE results, closed-form approximations are proposed for plastic limit loads of pipe bends. It is found that limit loads of pipe bends are smaller than those of straight pipes, but are close for deep and long cracks.