Experimental investigation and numerical simulation of the fatigue behavior of interference fitted specimens subjected to bolt clamping force

Interference fit process, as a popular method, is used in aerospace and automotive industries. General investigation of interference fit has been conducted on plain hole extensively. Nevertheless, interference fitted holes are practically subjected to bolt clamping force which may have different fatigue behavior than the plain hole. The objective of the present study is to extend the present knowledge about the fatigue behavior of interference fitted holes by investigating the subsequent bolt clamping force effect based on the experimental and numerical results. In this paper, Al-alloy 7075-T6 is utilized for fatigue test specimens. In relation to fatigue tests, three dimensional finite element analyses were used to explain the experimental results. By using finite element method, the interference fit process; bolt clamping and subsequent remote cyclic loading were simulated. The fatigue critical stresses on bolt clamped interference fitted (BIF) samples were compared with the corresponding stresses for interference fitted samples. The pre-stress distribution due to interference fitted hole, and its redistribution after bolt clamping forec and its interaction with remote loading were estimated The fatigue test results demonstrate that bolt clamping force applied on the interference fit plays positive effect on fatigue behavior and prolongs the fatigue life. The biggest life improvement for bolt preloads of 3409 and 6818 N is 2.5 and 7 times compared to the only interference fitted specimens, respectively.