Residual Stress Around the Fatigue Crack Front in a Rectangular Sample Cut from CT Specimen

Abstract

In this paper, an elastic–plastic finite element model was built to simulate the stress field around a fatigue crack in a standard CT specimen before and after splitting to obtain a rectangular specimen for further investigation. Plane stress and plane strain, as well as 3D simulations, were performed and compared. The simulations consist of two steps: (i) The standard CT-specimen undergoes cyclic loading until the fatigue crack tip achieves the middle of the specimen, and (ii) A rectangular sample with the crack to one half of its width was cut from the CT-specimen. A parametric plane strain study was carried out to determine the location of the cutting plane relative to the edge of the plastic zone, where the impact on the residual stress due to stress relief after cutting is negligible. It was also found that in the peripheral parts of the front close to the free surface, the stress is strongly influenced by the curvature of the crack front.