轨下支承失效对直线轨道动态响应的影响

EFFECT OF TRACK SUPPORT FAILURE ON DYNAMIC RESPONSE OF TANGENT TRACK

建立了基于Timoshenko梁模型的车辆/轨道耦合动力学模型,分析轨下支承失效对直线轨道动态响应的影响.钢轨被视为连续弹性离散点支承上的无限长Timoshenko梁,通过假设轨道系统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的车辆/轨道耦合系统激振模式,考虑轨枕离散支承对系统动力响应的影响.通过新型显式积分法求解车辆/轨道耦合动力学系统运动方程,由数值分析计算得到不同轨下支承失效状态下直线轨道的动态响应.结果表明,轨下支承失效对直线轨道变形及加速度有显著的影响,随着失效轨下支承个数的增加,轮轨相互作用力和轨道部件的位移、加速度将会急剧增大,将加速失效区段线路状况的恶化.

In order to investigate the effect of track support failure on dynamic response of tangent track, a vehicle-track coupling dynamic model is established, in which the rails are assumed to be Timoshenko beams resting on the discrete sleepers. The failure situation of track components under the tangent track is simulated by the abrupt changes of track stiffness along the track. The effect of the discrete sleeper supports on the coupling dynamics of the vehicle and track is taken into consideration by the excitation model of moving sleeper supported. As to the interaction of wheel and rail system, the creepage formulas of wheel/rail rolling contact are deduced, in which the lateral, vertical and torsional motions of rail are taken into account. The normal forces of wheel/rail are calculated by the Hertzian contact theory and the creep forces of wheel/rail in rolling contact 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. Effect of zero, two, four and six track supports in failure situation on tangent track dynamic response is analyzed and evaluated. The numerical results indicate that track support failure greatly affects dynamic response of tangent track. With the increasing of failure number, the wheel/rail normal forces, displacement and acceleration of track components increase quickly, which will deteriorate the track.