车体垂弯振型节点位置对其弹性振动的影响

根据车体的结构属性和质量分布将其考虑为多段变截面欧拉梁，建立包含车体一阶垂弯模态的车辆垂向动力学模型，研究车体一阶垂弯振型的节点位置对高速列车振动舒适度的影响，提出改善车体弹性振动的措施。基于变截面欧拉梁模型分析车体各截面的质量和抗弯刚度分布对模态振型的影响，发现不同截面之间的抗弯刚度和质量分布对整体模态振型影响显著，提高车体中部结构的抗弯刚度并减小其质量，可以增大节点间距和提高模态频率，而传统均直等截面梁模型则不能准确描述振型的幅值和节点位置。采用频域分析方法计算车辆在轨道随机激励下的振动响应，将车体垂弯振型节点调整到转向架二系上方附近时，车体的弹性振动水平显著降低，在车速为300 km/h时车辆舒适度指标可降低50%。

Effect of Modal Node Position of Vertical Bending of Car Body on Its Vibration

In order to study the effect of vertical bending modal node position on the ride comfort, the car body is considered as a variable cross-section Euler beam with multi-sections on the basis of its structural properties and mass distribution. The vertical dynamic model of the vehicle including the first-order vertical bending mode of the car body is established, and measures to improve the elastic vibration of car body are put forward. The relationship between parameters of variable cross-section beam and mode of vehicle body is studied. The analytical results indicate that traditional model with uniform cross-section beam cannot accurately describe the vertical bending mode. There are deviations between traditional model and vehicle body mode in the re ady state, especially in terms of amplitude and nodes position. Longitudinal distribution of bending stiffness and mass affects the mode shape of vertical bending. Increasing the bending stiffness and reducing the mass distribution in the middle of the car body can increase the space between nodes of bending mode, and increase the frequency of bending vibration. The response of vehicle under random excitation of track is obtained by frequency domain analysis method. When the bending nodes are near the bolsters of the vehicle, the elastic vibration of the car body decreases obviously. Also, ride comfort index in the middle of car body is reduced by 50% at the speed of 300 km/h.