基于能量法的轮对蛇行运动稳定性

为了分析轮对蛇行运动的形成机理与能量传递机制, 基于车辆系统动力学理论推导了轮对蛇行运动的能量表达式; 借助轮对运动参数的相位关系和能量表达式, 确定了轮对蛇行运动过程中各部分所做的功及其对应的能量传递路线; 通过数值仿真计算不同参数条件下的输入能量, 对比了踏面等效锥度、轮对质量、一系悬挂刚度与重力刚度等参数对轮对稳定性的影响规律。研究结果表明: 蠕滑力和锥形踏面的协同作用是轮对产生蛇行运动的根本原因, 蠕滑力中的刚度项通过调节纵、横向蠕滑率向轮对系统横向运动输入能量, 蠕滑力中的阻尼项耗散轮对系统的能量; 当输入能量大于耗散能量时, 轮对蛇行运动发散, 当输入能量小于耗散能量时, 蛇行运动收敛, 当输入能量等于耗散能量时, 轮对做等幅周期运动; 增大轮对质量和车轮踏面等效锥度不利于轮对的稳定性, 增大一系悬挂纵、横向刚度对轮对稳定性有利; 踏面等效锥度对轮对稳定性的影响最大, 当锥度由0.15增大到0.20时, 输入能量增大了约9.5倍; 一系悬挂刚度的影响次之, 刚度由75kN·m-1增大到100kN·m-1时, 输入能量减小了约60%;轮对质量影响最小, 轮对质量由1 000kg增大到2 100kg时, 输入能量增长了约1.1倍; 在锥形踏面下, 重力刚度对轮对稳定性的影响可以忽略。 

Hunting motion stability of wheelset based on energy method

In order to analyze the formation mechanism and energy transfer mechanism of wheelset hunting motion, the energy expression in the process of hunting motion was established based on the theory of vehicle system dynamics.According to the phase relationship of wheelset movement parameters and energy expression, the work of each part and energy transfer route during the hunting motion were determined.Input energy values under different parameters were calculated through numerical simulation, thus the influences of tread equivalent conicity, mass of wheelset, primary suspension stiffness and gravity stiffness on the stability of wheelset were compared.Research result shows that the synergy of creep force and cone tread is the fundamental cause of hunting motion.The stiffness force contained in creep force inputs energy into the wheelset lateral movement through the regulating action of wheel/rail longitudinal and lateral creep rate, and the damping term in creep force consumes the energy of wheelset system.When the inputenergy is larger than the dissipated energy in a cycle, the hunting motion diverges.When the input energy is less than the dissipated energy in a cycle, the hunting motion converges.When the input energy is equal to the dissipated energy in a cycle, the wheelset performs periodic motion with a constant amplitude.The enlargement of inertia term and conicity is harmful to the stability of wheelset, while the enlargement of primary stiffness is in favor of the stability of wheelset.Tread equivalent conicity has the biggest influence on the stability of hunting motion of wheelset.When conicity increases from 0.15 to 0.20, the input energy increases nearly by 9.5 times.Primary suspension stiffness comes the second.When the stiffness increases from 75 kN·m-1 to 100 kN·m-1, the input energy decreases nearly by 60%.The mass of wheelset is the smallest one.When the mass of wheelset increases from 1 000 kg to 2 100 kg, the input energy increases nearly by 1.1 times.Under the condition of conical tread, the effect of gravity stiffness has little influence on the stability, which can be ignored.