基于模态实验的单滑板受电弓全柔模型修正方法

FULL FLEXIBLE MODEL UPDATING OF SINGLE-STRIP PANTOGRAPH BASED ON MODAL TEST

动车组通过受电弓从接触网上获取电能,良好的弓网接触是列车受流的重要保障.随着列车速度的提高,弓网动态特性问题日益突出.受电弓在高速或更高速运行时,接触网不平顺、气动效应等高频激励,将激发受电弓的高频弹性模态及富有高频成分的弓网相互作用力.只考虑受电弓3个垂向自由度的三质量块模型不再适用于高频弓网动力学分析,为进行更高速下的受电弓动力学参数设计和弓网受流质量评估,需建立反映结构弹性模态的受电弓全柔模型.文章提出基于模态实验的受电弓全柔模型的修正方法.首先,开展一款新型单滑板高速受电弓的模态实验,获得260 Hz以内的两阶垂向耦合振动模态参数和6阶垂向弹性模态参数.然后,进行受电弓模态频率对材料参数的灵敏度分析,研究得到弓头、上臂和下臂的弹性模量和密度及弓头弹簧刚度,对受电弓的8阶垂向模态频率的影响显著,确定了模型修正的参数.最后,利用粒子群优化算法,获得与模态实验结果吻合度较高的修正全柔模型,其与实验结果的误差仅为5.2%.此外,提出基于模态置信度的振型识别方法,实现了迭代寻优过程中正确率为100%的模态自动识别.

Since electric multiple units obtain electricity from the catenary through the pantograph,a good pantographcatenary contact is essential for ensuring current collection quality for the train.With the increase of the running speed of the train,the issue of the pantograph-catenary dynamic characteristics becomes increasingly noticeable.As the traveling speed increases,the elastic modes of the pantograph and the high-frequency interaction between the pantograph and catenary will be excited by high-frequency excitation such as catenary irregularity and aerodynamic effects.The three lumped mass model that only considers the three vertical free degree of the pantograph is no longer suitable for highfrequency pantograph-catenary dynamics analysis.In order to design the dynamic parameters of pantographs at higher speed and evaluate the current collection quality of the pantograph-catenary system,a full flexible model of the pantograph that reflects the structural elastic modes is required.In this paper,an updating method based on the full flexible model of pantographs is proposed.Firstly,a new single-strip high-speed pantograph was tested,and modal characteristics of two vertical coupled vibration modes and six vertical elastic modes within 260 Hz were obtained.Then,an analysis on the sensitivity of the modal frequency of the pantograph to material parameters was conducted.It was found that the elastic modulus and density of the strip,upper arm and lower arm,and the spring stiffness of the pan head,have a significant influence on the eight vertical frequencies of the pantograph,and thus the model parameters to be updated were determined.Finally,by using particle swarm optimization,an updated full flexible model was obtained,which was in good agreement with the experimental results,with a deviation of only 5.2%.In addition,a modal identification method based on modal assurance criterion was proposed,which can achieve automatic modal identification in the process of model updating with 100% accuracy.