Effects of temperature and preload on fatigue behavior of train brake disc bolts

Given the rigorous conditions of high temperatures and diminished preload experienced by brake disc bolts in high-speed trains, this study conducted an experimental investigation into the fatigue failure of such bolts. Axial high cycle fatigue tests were conducted across five temperature levels and four preload levels. This paper proposed a temperature-related regression model to characterize the variation of fatigue strength under high temperature. The results indicated that the fatigue strength of the bolt material decreases with increasing temperature. When the temperature increased from 20 °C to 200 °C and 650 °C, the fatigue strength decreased by 29.7 % and 39.2 %, respectively. The fatigue life of the bolted joints correlated with the difference between the preload force and the peak fatigue load. The fatigue life was reduced by 17.8 %, 30.8 % and 33.7 %, when the preload force was reduced from 200Nm to 180Nm, 140Nm and 40Nm, respectively.