New multiaxial fatigue limit criterion for defective material: 1045 steel

Abstract

The aim of this paper is to present a fatigue life criterion for defective material. Defects are simplified to spherical or elliptical pore at surface of specimen under cyclic loading. The Finite Element method was used to determine stress distribution around defect for different morphology and loading modes. It is that shown a relevant mechanical parameter governing the fatigue limit for defective material could be the affected depth, which is the depth from the tip of defect to the bulk of sample where Crossland criterion was violated. A multiaxial fatigue criterion for defective material is proposed and validated for different metallic materials and loading conditions. The proposed criterion was able to take into account the defect size, shape of defect and loading mode. Results are good and show that the affected depth is a good parameter to characterize the influence of a defect on the fatigue behaviour.