Clamped member fatigue characteristics of bolted connections subject to out‐of‐plane loading

Abstract In the presence of significant cyclic loading, the design of safe and efficient structural connections requires accurate determination of the clamped member stresses, amongst other considerations. Connections with pretensioned bolts and loading applied parallel to the bolt axis constitute a challenging analysis task that is underrepresented in the literature. To address this, parametric finite element analysis was performed on a representative bolted connection subject to out‐of‐plane loading and comprised of an aluminum member and a pretensioned steel bolt – a typical configuration in the aerospace industry. Of particular interest were the flexural stresses and their contribution to fatigue damage along the member faying surface. The analysis results demonstrated that both the location and magnitude of the stress extrema varied greatly with the geometric and loading parameters considered. To quantify regions most susceptible to fatigue damage, an equivalent stress formulation in conjunction with a critical plane approach was implemented. Contour plots were generated illustrating these regions and regression analysis was performed relating the parametric geometry and load quantities to the maximum equivalent and principal stresses. Regions of greatest fatigue susceptibility were shown to vary both radially and tangentially about the fastener. The data presented are intended to improve both the efficiency and safety of bolted connections