冲角对低地板车辆轮轨接触状况的影响

针对城市轨道交通中低地板车辆车轮经常出现的轮缘严重磨耗现象，研究其轮轨接触状况，由于城市轨道交通中小半径曲线较多，存在较大的冲角，为研究冲角对轮轨接触状况的影响，利用轮轨型面测量仪测量运用中的70%低地板车辆车轮与钢轨型面，建立具有不同冲角的车轮与钢轨接触模型，在横向力与牵引力矩作用下应用非线性有限元法进行弹塑性接触计算，分析不同工况下的等效应力及接触斑的变化规律，研究冲角、横向力与牵引力矩对钢轨接触状况的影响。通过计算分析得出以下结论：具有不同冲角的轮轨接触斑形状几乎相同，踏面接触斑近似矩形，轮缘接触斑相对狭长，容易造成轮缘磨耗；冲角增大，轮缘接触斑相对踏面接触斑的超前值增大；随着冲角的增大，轮轨最大等效应力逐渐增大，磨耗功率增大，故在轮轨型面匹配和车辆结构设计中应尽量将轮轨冲角控制在1°以内。

Influence of Attack Angle on Wheel/rail Contact of Low-floor Vehicles

The flange of wheels which are used in the urban railway wear severely. Aiming at this phenomenon, the wheel/rail contact is studied. Besides, there is big attack angle in the urban railway because of the small radius curves. So to study the influence of attack angle on the wheel/rail contact is important. The wheel profiles of the applied 70% low-floor vehicles and rail profiles are measured through the wheel/rail profile admeasuring apparatus. The elastic-plastic contact models with the measured wheel/rail profiles are calculated by the nonlinear finite element method when the wheel is under the effect of the lateral force and the driving torque. Through the calculation, the change laws of the Von Mises stress and the contact patches are analyzed at different working conditions and the influence of attack angle, lateral force and driving torque on the wheel/rail contact is studied. Some conclusions are indicated as follows. The shapes of wheel/rail contact patches with different attack angles are almost same. The patch shapes on the tread approximate rectangle and the ones on the flange are relatively long and narrow which can easily cause flange abrasion. With the attack angle increasing, the values that the position of flange contact patch is ahead of tread contact patch increase and the maximum equivalent Von Mises stress between wheel and rail increases gradually. The attrition power also increases. So when designing the wheel/rail profile match and vehicle structure, the attack angle should be kept within 1° as possible.