Experimental evaluation of cyclic stresses on axially loaded bolted joints

Abstract

The bolted joints fatigue behavior was analyzed by using torque as tightening method and steel and aluminum as members’ material. The bolt used in the current study was the M6 class 8.8. The bolt preload value was calculated based on the bolts’ elongation in each applied torque. The fatigue limit increases as the torque increases up to the torque limit to fracture the bolt. This behavior was seen in both members’ material. Steel members support higher torque before bolt fracture. An analytical study also evaluated the relationship between the cyclic stress amplitude and the mean stress experienced by fatigue-tested bolts based on the available models for joint stiffness. The results were compared to the bolt fatigue diagram by Burguete and Patterson. The herein studied linear elastic theoretical models showed wide range in the correlation between stress amplitude and mean stress.