Predictions of Propagation Behavior of Semi-Elliptical Slant Surface Cracks in Residual Stress Fields Based on Simulations of the Partial Elastic Contact of Crack Surfaces

Abstract

In residual stress fields, the so-called partial elastic contact of crack surfaces sometimes occurs, where a fatigue crack is closed at the crack mouth while it is open at the crack tip. The partial elastic contact has a significant effect on the lives of fatigue cracks. However there are few studies on the partial elastic contact of crack surfaces for three-dimensional cracks. In this paper, the propagation paths and lives of semi-elliptical slant surface fatigue cracks are predicted. The finite element method was employed for these simulations. The residual stress was introduced by applying an equivalent nodal force in correspondence to an initial strain to each finite element. The results of the propagation paths and lives of simulations considering the partial elastic contact of crack surfaces differed from those without the consideration of the elastic contact. Especially the estimated results of crack propagation rate sometimes brought one-order difference. These results demonstrate the necessity of simulation considering the partial elastic contact of crack surfaces.