基于模态贡献的动车组车体弹性振动控制

Car body elastic vibration control in EMUs based on modal contribution

动车组车体结构轻量化设计会导致结构柔性增加,随着动车组运营里程的增加,轮轨磨耗的加剧,车体在运行过程会出现抖车、晃车等异常弹性振动现象,进而影响乘坐舒适性和运行安全性。因此,从模态贡献、模态设计和模态控制等角度出发分析产生该异常振动的原因。基于动车组车体模态修正和模态试验结果,建立车体有限元模型;根据车体工况,将车体模态处理为自由模态,提取结构模态参数;基于模态分析理论和模态贡献原理,分析车体结构弹性模态振型,并依据车体模态位移计算结构模态贡献因子;分析控制车体弹性振动的模态匹配方法与传递函数控制方法。结果表明,对车体垂向振动贡献较大的模态依次为车体一阶垂弯、一阶菱形、二阶菱形、一阶扭转等模态,对横向振动贡献较大的模态依次为一阶横弯、一阶菱形、二阶菱形、一阶扭转模态。引起车体弹性振动的主要因素有轨道激扰、转向架蛇行、转向架模态、车下设备悬挂参数等。轮对、构架、车体等构件的刚性自振频率应满足隔振要求,车体一阶菱形弹性模态频率与构架刚性、弹性频率要有效隔离,可降低车体异常弹性振动;增大车体结构阻尼比可减小加速度传递函数幅值,提高乘坐舒适性,当车体结构阻尼比从0.015提高至0.150时,平稳性指标可改善13%,提高结构阻尼可显著降低车体振动。

The lightweight design of the car body structure in EMUs leads to an increase in structural flexibility, and with the increase in the operating mileage and the deterioration of wheel-rail wear, the car body suffers from worsening abnormal elastic vibrations during operation, such as jittering and lurching, which affect riding comfort and operational safety. This paper was intended to analyze the causes of such abnormal vibrations, from the perspectives of modal contribution, modal design and modal control. Firstly, based on the modal correction and modal test results of the car body, a finite element model of the car body was established. Secondly, according to the working conditions, the car body was processed into a free modal, and the structural modal parameters were extracted. Then, based on the modal analysis theory and the principle of modal contribution, the elastic modal shapes of the car body structure were analyzed, and the structural modal contribution factor was calculated according to the car body modal displacement. Finally, the modal matching method and transfer function method were analyzed for the elastic vibration control of the car body. The results show that the modals that contribute greatly to the vertical vibration of the car body in the order of magnitude are as follows: the first-order vertical bending, the first-order diamonding, the second-order diamonding, and the first-order torsioning, and the modals that contribute greatly to the lateral vibration in the order of magnitude are as follows: the first-order lateral bending, the first-order diamonding, the second-order diamonding, and the first-order torsioning. The main factors that cause the elastic vibration of the car body are the track disturbance, the bogie hunting motion,the bogie modal, and the suspension parameters of the underfloor equipment. The rigid natural vibration frequency of the wheelset,frame, car body and other EMU components should meet the vibration isolation requirements, and the first-order diamonding elastic modal frequency of the car body should be effectively isolated from the rigidity and elastic frequencies of the frame, to reduce abnormal elastic vibration of the car body. An increase in the damping ratio of the car body structure can reduce the amplitude of the acceleration transfer function and improve the riding comfort. Specifically, an increase in the damping ratio of the car body structure from 0.015 to 0.150can improve the running stability index by 13%, so increasing the structural damping can significantly reduce car body vibration.