Fatigue behaviour of stainless steel bolts in tension and shear under constant-amplitude loading

Abstract

This paper experimentally investigates the fatigue performance of stainless steel bolts in tension and shear under constant-amplitude loading. The static behaviour of normal bolts and Hollo-bolts subjected to monotonic loading was initially reported aiming to obtain the ultimate strength. Periodic loading tests were thereafter performed to acquire tensile and shear fatigue life under various stress ranges in which failure modes and cycles were recorded. From test results, S-N curves were summarised through regression analysis, followed by numerical modelling which was used to investigate the stress distribution. Finally, different design codes were selected to estimate the fatigue limit of bolts in tension and shear. It was found that both coupon tests and monotonic loading tests are required to determine the material property of stainless steel bolts. Regions adjacent to bolt nuts are the most vulnerable parts in terms of fatigue in tension, and the maximum principal stress dominates the fatigue life of fasteners with threads in shear plane. The fatigue strength of Hollo-bolts is slightly higher than that of normal bolts. Moreover, although current design codes can conservatively estimate the fatigue behaviour, provisions for shear fatigue are recommended to be modified for higher accuracy and better application.