Numerical Investigation to Examine the Effect of Introducing a Crack in a Residual Stress Field

This paper presents a detailed two dimensional finite-element study to examine the effect of introducing a crack either progressively or instantaneously into a residual stress field. A progressive crack is defined as a crack which is introduced in fixed increments of crack extension until the desired crack length is achieved. An instantaneous crack is one in which a crack of the required length is introduced instantaneously into the finite-element mesh. Inspection is made of the crack tip fields and the crack opening displacements. A modified definition of the J-integral, which accounts for the initial plastic strain due to residual stress, is assessed, in order to examine its ability to characterise the intensity of the near crack tip fields. The implications of the results on fracture assessment of structural components are discussed.