Abstract:The integrity of bolted joint in braking disc system is critical to the good quality of braking performance. A thermo-mechanical coupling finite element model is established to investigate the load variation of bolted joint in axle braking disc of railway vehicle under continuous downhill braking condition. The transient temperature gradient in the brake disc is the key mechanism for the variation of bolt loads. The bolt tension drops firstly and then bounces back, while the bending

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... ent is introduced in the bolt due to temperature non-uniformity. The circumferential bending moment is significantly higher than that in the radial bending direction. The bolt load variation decreases with the increase of the convection heat transfer coefficient, but the influence is gradually reduced when the convection heat transfer coefficient reach a certain value. The mismatch of thermal expansion coefficient of bolt with surrounding structure causes the increased variation of bolt tension and bending moment, which may cause either the loosening or the bending failure of bolt joint. The initial preload has no much influence on the thermally-induced bending moment but a moderate influence on the variation of tension.