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以热塑性聚氨酯弹性体(TPEE)的扣件胶垫为研究对象,首先利用万能试验机测得其荷载-位移非线性曲线。然后,借助非线性静力分析的有限元模型,计算车辆静载与弹条扣压共同作用下该类扣件胶垫的位移幅值及其对应的静刚度。最后,运用车辆-轨道垂向耦合随机振动分析模型,探讨聚氨酯胶垫的常量刚度、频变刚度与幅频变刚度对车辆-轨道耦合系统随机振动频响特征的影响规律。研究结果表明:聚氨酯胶垫的静刚度具有显著的非线性特征,而且在20 k N扣压力与80 k N静轮载共同作用下聚氨酯胶垫的静刚度在19.1 k N/mm~37.9 k N/mm范围内变化,其均值与规范中假设的线性常量静刚度26.7 k N/mm相近;另外,与聚氨酯胶垫的幅频变刚度相比,它的常量刚度会严重低估轮轨系统65 Hz~150 Hz的频域响应。因此,如果车辆-轨道系统中有刚度非线性较强的高分子材料,就必须综合考虑这些材料刚度的幅变与频变特征,否则将难以准确预测轮轨系统及其周边环境振动的频域响应。
Taking thermoplastic elastomer elastomer (TPEE) as fastener, the load-displacement nonlinear curve was first measured by universal testing machine. Then, with the help of the finite element model of nonlinear static analysis, the displacement amplitude and the corresponding static stiffness of such fasteners are calculated under the joint action of dead load and buckling. Finally, the random vibration analysis model of vehicle-track vertical coupling was used to investigate the influence of the constant stiffness, frequency-varying stiffness and amplitude-frequency stiffness on the random vibration frequency response of vehicle-track coupling system. The results show that the static stiffness of polyurethane pad has significant non-linearity, and the static stiffness of polyurethane pad is between 19.1 kN / mm and 37.9 kN under the combined effect of buckle pressure of 20 kN and static load of 80 kN / mm, with a mean value similar to the assumed static linear stiffness constant of 26.7 kN / mm in the specification. In addition, its constant stiffness will significantly underestimate the wheel-rail system’s 65 Hz ~ 150 Hz frequency domain response. Therefore, if there are highly rigid and non-linear polymer materials in the vehicle-track system, the stiffness and frequency-varying characteristics of these materials must be considered together otherwise it will be difficult to accurately predict the frequency domain of the wheel-rail system and its surrounding environment response.