An analysis of crack growth and life in a sharply notched cylinder component under low-cycle fatigue.

Abstract

Elastic-plastic stress/strain analyses were performed for the circumferentially grooved component using the finite element method. The semielliptical surface crack originating at the notch root changes its shape, being influenced by the stress/strain gradients produced in the cross section of the notched component. Such a change in the shape of the surface crack was successfully analyzed in terms of the elastic-plastic fracture mechanics. The transition from the semielliptical to circumferential crack, which occurred in the process of the crack extension at the notch root, was also satisfactorily predicted in the present analysis. The number of cycles required for the semielliptical crack to reach the circumferential crack and for the circumferential crack to grow to the final failure were estimated through the proposed elastic-plastic fracture mechanics approach. The calculations were in quite good agreement with the test data.