Fatigue behaviour of blind bolts under tensile cyclic loads

This study presents an experimental investigation on the fatigue performance of a blind bolt under axial-tension cyclic loads. Static, constant-amplitude, and variable-amplitude fatigue tests on standard bolts and blind bolts are carried out. The bolt failure modes, static tensile force-displacement relationships, and fatigue life are presented. Based on the experimental results, S-N curves of the bolts under constant-amplitude fatigue tests are obtained by means of regression analysis, and the influence of the load amplitude as well as the load ratio on the fatigue performance of blind bolts are examined. It is found that S-N curves follow a power function with negative exponent, and exhibit similar S-N curves to standard bolts under higher load ratio. Meanwhile, the fatigue life of blind bolts under variable-amplitude loadings is estimated by using Miner's linear cumulative-damage theory. The fatigue strength of blind bolts under variable-amplitude fatigue loading is lower than the corresponding value for constant-amplitude fatigue tests. Finally, the fatigue strength of blind bolts is assessed by comparing the test results with existing specifications. It is concluded that the fatigue performance of blind bolts can be conservatively estimated by the corresponding specification of design codes.