高速动车组制动盘螺栓断裂分析及优化方案

Analysis and Optimization Scheme of Brake Disc Bolts Fracture for High-Speed EMU

针对高速动车组运用中出现制动盘螺栓断裂问题,选取典型断裂螺栓进行失效分析,并在振动和热负荷环境下对制动盘紧固结构受力状态进行试验和分析.研究发现:制动盘螺栓断裂为低应力疲劳断裂,在高于50g的振动水平下,根据不同的振动频率,摩擦环相对盘毂产生微小相对位移,螺栓承受一定弯曲应力;在长大坡道等极端工况下运行时动车组采用摩擦制动,制动盘各部件由于长时间承受高热负荷及较大的温度梯度,使螺栓承受弯曲应力.针对制动盘螺栓受力情况,提出了变截面螺栓的改进方案,弯曲疲劳试验结果对比表明,新结构螺栓弯曲疲劳性能显著增强,可用于既有动车组轴盘螺栓的替换.

Aiming at the problems of the brake discs in the operations of the high-speed EMU,the failure analysis of typical fractured bolts was carried out,and the stress state of the fastening structure of the brake disc was tested and analyzed under the vibration and heat load environment. It is found that the fracture of brake disc bolt should belong to low stress fatigue fracture. At a vibration level higher than 50 g,the friction ring has a slight relative displacement relative to disk hub according to the different vibration frequency,and the bolt is subjected to a certain bending stress. In the extreme operating conditions such as long ramps when the EMU with friction brake,the brake disc parts will bear bending stress that withstand high heat load and a large temperature gradient for o long time. Aiming at the force of brake disc bolts,an improved scheme of variable crosssection bolts is proposed. The results of the bending fatigue test show that the bending fatigue performance of the new structure bolts is obviously enhanced and can be used to replace the axle bolts of the existing Highspeed EMUs.