Effects of stop hole on crack turning, residual fatigue life and crack tip stress field

Abstract

The aim of this paper is to research the effects of stop hole on crack turning, residual fatigue life and crack tip stress field, in which the location, size and shape of stop hole are considered. The numerical model is established according to M-integral technology, and crack turning angle is determined by maximum hoop stress criterion. The calculation results show that stop hole location has a significant effect on crack turning angle and residual fatigue life, and it should be drilled with a reasonable distance in vertical and horizontal direction around crack tip to achieve a better residual fatigue life retardation effect. The larger the stop hole size is, the wider effect range of stop hole on crack turning and residual fatigue life will be. The effects of elliptical stop hole on crack turning angle and residual fatigue life retardation are greater than that of round hole when the distance in vertical direction increases. Crack tip stress distribution is changed by increasing σ y and decreasing σ x , and the most dramatical changes occur at the circumferential direction of 90° and 270°.

Numerical analysis of crack propagation in fretting fatigue specimen repaired by stop hole method

“…Therefore, crack arrest technology in crack propagation stage is widely used. For example overload technique [28][29][30], cold expansion [31][32][33][34], indentation (dimple) [35][36][37] and stop hole [30,35,[38][39][40][41][42]. A single overload causes crack closure, tip dullness and strain hardening near the tip.…”

“…Fanni, Fouda [43] optimized the shape of the stop hole, compare with the circular hole, and they obtained a better fatigue life extension effect. The effects of deflecting hole on the crack direction and residual life were studied by Hu et al [42] through Extended Finite Element Method (XFEM). The comprehensive effect of stop hole and overload technology is studied by Lu [30] experimentally.…”