复杂振动和交变温度工况下高铁梯形螺栓连接松动规律

Trapezoidal bolt connections serve as the primary joining method for equipment compartment skirts, base plates, and other components in high-speed railway trainsets. However, during service, these bolts are subjected to prolonged exposure to severe vibration loads and alternating high and low temperature environments, leading to easy loosening and potential fatigue fractures. This poses risks and challenges to the reliable operation of HSR trains. To address this issue, an accurate finite element model of trapezoidal bolt connections was established to simulate lateral, longitudinal, bending, and torsional vibrations, as well as alternating temperature loads. By the model, the loosening behavior of trapezoidal bolts was analysed under the individual and combined effects of these vibrations and alternating temperature loads. Furthermore, the influences of initial preload, friction coefficient, and material of the clamped components on bolt loosening under lateral vibration conditions were systematically investigated. The research findings indicate that the lateral vibration is the primary load form causing trapezoidal bolt loosening, the bending vibration can only lead to bolt loosening in specific circumstances, while the longitudinal vibration, torsional vibration, and alternating temperature loads hardly cause loosening. Furthermore, the effects of vibration and alternating temperature loads are independent of each other. Moreover, the effects of vibration and alternating temperature loads are independent of each other. Compared to ordinary thread and pipe thread structures, trapezoidal bolt connections exhibit slightly inferior locking performance but demonstrate a 30% reduction in stress concentration under the same conditions, which will significantly enhance the load-bearing capacity and fatigue resistance of trapezoidal bolt connections.