Post yield fracture mechanics

Abstract

A simple crack model, which includes a representation of plastic relaxation, is used to discuss the fracture of high and low strength materials in the post yield regime. A correspondence is set up between the fracture criteria given by the present model and the familiar results of linear elastic fracture mechanics. The model is used to discuss the fracture of reinforced composite materials, polymers and turbine and pressure vessel steels. An apparent fracture toughness is defined and it is shown that this quanitity reduces to the plain strain fracture toughness for cases where there is limited plastic deformation. It is found that the plane strain fracture toughness controls the mechanics of fracture even in the post yield regime. The effect of notch root radius on measured fracture toughness values is also discussed.