On the fatigue behavior of cold expanded fastener holes subjected to bolt tightening

Cold expansion literature has been generally devoted to open hole specimens. Nevertheless, cold expanded specimens are practically used in bolted and riveted connections possessing different fatigue behavior than open hole specimens. This paper has sought to investigate the fatigue behavior of cold expanded specimens after being subjected to bolt tightening. Fatigue tests and numerical simulation were conducted to study the role of bolt clamping force on the residual stress distribution, fatigue life and failure mode of bolted cold expanded specimens. The results significantly reveal that bolt clamping contributes more positive effect and prolongs the fatigue life additionally. However, it may also change the failure mode from notch fatigue to fretting fatigue.