Review and synthesis of stress intensity factor (SIF) solutions for elliptical surface cracks in bolts under nut loading: A Tribute to Agustín de Betancourt
This paper presents stress intensity factor (SIF or K) solutions for a semi-elliptical surface crack in a bolt subjected to remote tension and nut loading. Solutions were numerically computed by a 3D finite element method (FEM) with quarter-point singular isoparametric elements along the crack line. The SIF was calculated through the stiffness derivative method, by using a virtual crack extension technique to compute the energy release rate. Solutions are compared in the matter of SIF values at the center of the crack front and at the external surface of the bolt, and a wide range of crack aspect ratios and relative crack depths are studied, in order to provide the engineer with solutions applicable to different real situations in fracture mechanics or damage tolerance analyses such as static or cyclic (fatigue) loading, environmentally assisted cracking or corrosion-fatigue. Results of the analysis are relevant to determine the crack path evolution in threaded connections. In Memoriam: The paper is dedicated to the memory of the prominent Spanish engineer Agustín de Betancourt.