地铁扣件锚固螺栓断裂原因分析

针对部分地铁线路扣件锚固螺栓发生断裂、影响运营安全的问题,开展了现场测试,获得了螺栓扭力矩与轴力间的关系.基于实测数据,考虑弹簧垫圈的空间形状不规则性、接触应力的非均匀性,以及不同部件间的非线性接触作用等,建立精细化扣件螺栓有限元模型,分别对安装单、双弹簧垫圈时螺栓各部件的力学特性进行对比分析,结果表明:采用双垫圈较采用单垫圈,由于在压紧状态下还能提供剪切变形,螺栓轴力在列车荷载作用下增幅小,破坏的可能性大大降低;由于弹簧垫圈的特殊形状,螺帽与垫圈局部接触位置存在应力集中、螺帽受到较大偏载作用,是螺栓与螺帽结合位置易产生裂纹并扩展破坏的重要原因,该分析结果与现场实际情况相吻合.

Fracture Reason Analysis of Screw Bolt for Subway Fastener

Fastener screw bolt fracture affects the operation safety of subway lines. Field experiments were carried out to investigate the relationship between the torque and axial force of screw. Based on the measured data and a consideration of the irregular spatial shape of spring washer, non uniformity of the contact stress, and nonlinear contact between different parts, fine finite element model of fastener screw was established. The mechanical characteristics of each component of the screw with single and double spring washers were analyzed respectively. The results show that in comparison with the single washer, the axial force of screw with double washers increases less under train load and the possibility of damage decreases because of the shear deformation in the compression state. The special shape of spring washer causes stress concentration in the joint of nut and washer and a partial load on nut, which is a major reason for the crack. The analysis results agree well with the actual situation.