Three-dimensional stress concentrations at circular pin holes in clearance-fit lugs

Abstract

The influences of thickness and bonding clearance on stress concentration factors (SCFs) at circular holes in pin-loaded straight lugs are systematically investigated using the finite element method. The three-dimensional effect on stress concentration at pin hole is strong when the thickness B of lug is higher than the radius R of pin hole. The maximum tensional SCF K max normalized by its corresponding plane stress solution K p―σ increases with increasing B/R when B/R is higher than 2 for all of r/R (the radius of pin to that of lug), and also increases with decreasing r/R for a given B/R. It is also found that the plane stress SCF K p―σ nearly remains a constant when r/R < 0.98, but is strongly sensitive to r/R and increases by 30% with r/R changing from 0.98 to 1. On the other hand, the friction coefficient, Young's modulus and the load level have also influences on stress concentrations, which should not be neglected in design of structures. An empirical formula of the maximum SCF is obtained for convenience of engineering applications.