The development of mode I, linear-elastic stress intensity factor solutions for cracks in mechanically fastened joints

Abstract Accurate representation of crack tip stress intensity is an essential part of the assessment of the damage tolerance capability of aerospace structures. In typical applications, mode I stress intensity solutions are taken as factorial combinations of the fundamental form and various boundary correction factors for any given geometry and applied load. Total solutions are then developed by superimposing individual solutions for various load conditions. This technique is discussed for typical structure involving loaded fastener holes. Tabulated and plotted results are presented for cracks emanating from both open and loaded holes in finite width plates, lugs and multi-fastener joints. In the case of the open hole and lug solutions, the results are compared with published finite element values. The expressions presented herein lend themselves to programming on a digital computer. Once established, they afford the engineer the ability to develop accurate K I solutions for a wide range of applications which are typical of the geometry/loading configurations encountered in the damage tolerance analysis of mechanically fastened joints. Equally as important, they offer accuracy comparable to that obtained with finite element modeling at a fraction of the cost.