轨下支承失效对车辆系统动态响应及乘坐舒适度的影响

Effect of Track Support Failure on Dynamic Responses and Riding Comfort of Vehicle System

建立了基于Timoshenko梁模型的非对称车辆/轨道耦合动力学模型,分析轨下支承失效对车辆乘坐舒适度的影响。钢轨被视为弹性离散点支承上的无限长Timoshenko梁,通过假设轨道系统垂向支承刚度沿纵向分布发生突变来模拟轨下支承失效状态。推导了考虑钢轨横向、垂向和扭转运动的轮轨滚动接触蠕滑率计算公式。利用Hertz法向接触理论和沈氏蠕滑理论分别计算轮轨法向力及轮轨滚动接触蠕滑力。采用移动轨下支承模型分析离散的轨枕支承对系统动力响应的影响。利用新型显式积分法求解车辆/轨道耦合动力学系统运动方程。乘坐舒适度评价采用Sperling指标,通过数值分析,得到直线轨道连续从0到6个轨下支承失效对车辆动态响应及乘坐舒适度的影响。结果表明,轨下支承失效对车辆系统位移、加速度有显著的影响,随着轨下支承失效个数的增加,轮轨力和车辆系统的位移、加速度将会急剧增大,乘坐质量和乘坐舒适度指标呈线性增大,但数值很小。

In order to investigate the effect of track support failure at tangent track on dynamic response of vehicle, a non-symmetrical vehicle-track coupling dynamic model is established, in which the rails are assumed as Timoshenko beams resting on the discrete sleepers. The failure situation of track components under the rails is simulated by abrupt change of track stiffness along the track. The effect of the discrete sleeper support on the coupling dynamics of the vehicle and track is taken into consideration by the backward moving sleepers. The creepage formulas of wheel/rail rolling contact are deduced, in which the vertical and lateral motions of the track are considered. The normal forces of wheel/rail are calculated by Hertzian contact theory and the creep forces are decided by the nonlinear creep theory of Shen et al. The motion equations of the vehicle/track coupling system are solved with the new explicit integration method. Ride comfort of vehicle is evaluated by the Sperling＇s ride index. Effects of track supports in failure situation on tangent track dynamic response and ride comfort are evaluated in succession from zero to six supports. The numerical results indicate that track support failure greatly affects the dynamic response of the displacements and accelerations of vehicle. When the failure numbers increase, the wheel/rail normal forces, the displacements and accelerations of vehicle components increase quickly, and Sperling＇s ride index, including the ride quality and ride comfort, increase linearly but the value is rather small.