Fatigue Life of Pin-Loaded Lugs: Friction and Clearance Effects

Abstract

Lugs serve as crucial linkages in aircraft structures to connect components and transmit loads and motions. Because of their mechanical functions, their failure would lead to severe consequences. To ensure structural safety, factors that could affect the fatigue performance should be well considered and quantified. In this paper, the effects of the inevitable friction and clearance between the lug and load pin are quantified. The fatigue lives of straight and oblique lugs are predicted by using the classical local stress approach and a modified theory of critical distances. Satisfactory correlations between the predictions and extensive experiments are achieved.