Abstract: In order to reveal the constant amplitude fatigue failure mechanism of bolt pin shaft in pin hinge joint of spatial structure and explore the influencing factors of fatigue strength, the fatigue test of M36 bolt pin shaft was carried out. Based on the self-designed loading device, the constant amplitude fatigue tests of 9 bolt pin shafts were conducted. The nCode fatigue simulation analysis software was used to do parameterized analysis of 32 models with 4 factors for fatigue simulation. The results shows that the maximum equivalent stress in the pin hinge joint appears at the junction of the inner and outer padeye and the bolt pin shaft, where the stress concentration is serious. Neglecting unfavorable factors such as initial defects of the specimen and experimental loading, the fatigue life obtained from numerical simulation is partially higher than the corresponding fatigue test life. The S-N curve and theoretical fatigue life estimation formula of the bolt pin shaft are obtained based on linear fitting. The constant amplitude fatigue strength of bolt pin shaft is positively correlated with the loading stress ratio and bolt diameter, negatively correlated with the initial growth of pin hole clearance, and has nothing to do with the ear plate spacing. The sensitivity order of influencing factors of constant amplitude fatigue performance of bolt pin shaft is: the gap of pin hole, the bolt diameter, the loading stress ratio, the ear plate spacing.

Key words: space structure, bolt pin, constant amplitude fatigue, numerical simulation, parametric analysis