Crack Extension and Propagation Under Plane Stress

Experiments are described that reveal the three-dimensional character of the plastic zone in front of notches and cracks in plates of an Fe-3Si steel and a plain carbon steel. These define the plane-stress regime as a function of applied stress and plate thickness. They also provide a rationale for the DM (dugdale - Muskhelishvili) model as a tentative elastic-plastic solution of a crack under plane stress. Refinements that offer a way of taking work hardening and rate - sensitive plastic deformation into account are described. In this way, unnotced tenile properties - the stress-strain curve and reduction in area - are used to calculate plastic-zone size, crack-tip displacements and strains, the crack -…