Crack-Surface Displacements for Cracks Emanating from a Circular Hole under Various Loading Conditions

Williams, T. N., Newman, J., Jr., & Gullett, P. (2010). Crack-Surface Displacements for Cracks Emanating from a Circular Hole under Various Loading Conditions. In John Yates, Eann Patterson, Feargal Brennan and Andrew Sherry (Eds.), Fatigue and Fracture of Engineering Materials and Structures. Wiley-Blackwell. 34, 250-259.

The purpose of this paper is to calculate and develop equations for crack–surface displacements for two-symmetric cracks emanating from a circular hole in an infinite plate for use in strip-yield crack-closure models. In particular, the displacements were determined under two loading conditions: (1) remote applied stress and (2)uniform stress applied to a segment of the crack surface (partially loaded crack). The displacements were calculated by an integral-equation method based on accurate stress–intensity factor equations for concentrated forces applied to the crack surfaces and those for remote applied stress or for a partially loaded crack surface. A boundary-element code was also used to calculate crack–surface displacements for some selected cases. Comparisons made with crack–surface displacement equations previously developed for the same crack configuration and loading showed significant differences near the location where the crack intersected the hole surface. However, the previous equations were fairly accurate near the crack-tip location. Herein an improved crack–surface displacement equation was developed for the case of remote applied stress. For the partially loaded crack case, only numerical comparisons were made between the previous equations and numerical integration. A rapid algorithm, based on the integral-equation method, was developed to calculate these displacements. Because cracks emanating from a hole are quite common in the aerospace industry, accurate displacement solutions are crucial for improving life prediction methods based on the strip-yield crack-closure models.