Fracture resistance of a structural steel as characterized by the strength of the plastic stress singularity

Fracture resistance, characterized by the strength of the plastic stress singularity, was determined at failure load and crack length using three-dimensional elastic--plastic finite-element analysis of 29 A36 steel fracture specimens that had been tested at --50 deg F. This measure of fracture resistance was insensitive to specimen size, geometry, parent plate and heat, provided that the specimens were either of full plate thickness or were taken from the midthickness of parent plates. On the other hand, the fracture resistance of full-thickness plates was not reliably estimated from the fracture specimens taken from the thickness 1/4 point or near the surface of the parent plates. The computed variation in crack-front through-thickness response at 10% of max. load was confirmed by comparison with elastic results. Elastic--plastic response at max. load, including the tendency to more extensive yielding in smaller specimens, was similar to that indicated by other authors. Several parameter studies demonstrated the insensitivity of the results to the finite-element mesh design. 12 ref.--AA