Verification of the Small Region Yield During Three-point Bending Fatigue Test by the Use of Cutting Method.

Abstract

If the maximum stress at the critical point is used to evaluate the bending fatigue strength of a crowned arc-notch three-point bend specimen, the fatigue strength will be greater than the yield point, and yielding is considered to occur in a small region near the critical point. In this study, in order to confirm the yielding phenomenon in bending fatigue tests, the stress-strain relationship during the loading and unloading process was investigated using nonlinear FEM analysis, and the residual strain at the critical point was measured using the presented back-cut method. As a result, the residual strain at the critical point was confirmed. So, it was clarified that small range yielding should be considered in the bending fatigue strength design of mechanical elements with stress concentration.