Theoretical and Experimental Analysis of Surface Cracks Emanating from Fastener Holes

Abstract

The finite element-alternating method is used to determine stress intesity factors along the periphery of a part-elliptical crack emanating from a fastener hole in a finite-thickness plate. The method performs a sequence of iterations between an analytic solution for an elliptical crack embedded in an infinite solid and a finite element solution for a finite-thickness uncracked plate with a fastener hole to obtain the stress field near the crack, the stress intensity factor and the crack opening displacements. Mode-one stress intensity factors around the crack front are presented for three classes of crack location relative to the hole and numerous crack shapes and sizes. Calculations are performed for cracks emanating from both loaded and unloaded fastener holes. Crack opening displacements for all cases are presented. The results of this study are compared to static fracture tests in polymethylmethacrylate and with experiments and estimates of other authors.