New fatigue limit assessment approach of defective material under fully reversed tension and torsion loading

This paper presents a new approach to predict the high cycle fatigue limit of defective material submitted to multiaxial loading. Defects are simplified to a half spherical void at the surface of a specimen. Finite Element (FE) method is used to determine stress distribution around defect for different sizes and loading levels. Papadopoulos high cycle fatigue criterion is used to calculate equivalent stress around defect. Based on stress analysis, a definition of affected area is proposed, in which the Papadopoulos criterion is violated. The evolution of the affected area, versus the amplitude of loading and defect size leads to determine fatigue limit for defective material. Results are in good agreement with experimental investigations and show that the affected area is a good parameter to predict the influence of a defect on multiaxial fatigue behaviour