Effect of bolt tightening on the fatigue behavior of GLARE double shear lap joints

In this paper, the effect of bolt torque tightening has been investigated on the fatigue behavior of GLARE in double shear lap configuration. To do so, experimental fatigue tests were conducted using GLARE3-5/4-0.4 specimens with applied torques of 0 (finger tightened), 2 and 4 Nm at different cyclic longitudinal load ranges to achieve the stress-life (S-N) curves. The results revealed that applying and increasing the clamping force enhances the fatigue life of the GLARE specimens. Furthermore, comparison of fatigue test results of GLARE and available monolithic aluminum alloy 2024-T3 plates indicated when the applied load range is low, the effect of clamping force is more noticeable in GLARE specimens due to longer fatigue crack growth life of GLARE. Also, the occurrence of fretting fatigue didn't reduce the fatigue life of GLARE specimens considerably in contrary to aluminum sheets because of the laminated structure of GLARE. The obtained results can provide insights in designing bolted GLARE joints with superior fatigue in-service performance.

Automated summary

This study investigated the effect of bolt torque tightening on the fatigue behavior of GLARE, finding that applying and increasing clamping force can enhance the fatigue life of GLARE specimens. Compared to aluminum alloy 2024-T3 plates, the effect of clamping force is more noticeable in GLARE specimens due to longer fatigue crack growth life of GLARE under low load ranges.