风与轨道不平顺随机激励下车辆-轨道系统耦合振动的概率密度演化分析

Probability density evolution analysis of coupled vibration of vehicle-track system under random excitation of wind and track irregularity

  • 摘要: 依据车辆‑轨道耦合动力学及概率密度演化理论,建立了考虑横风和轨道不平顺双重随机因素作用的车辆‑轨道系统耦合振动模型。采用N维超立方体点集生成离散随机频率和相位代表点集,基于随机谐和函数方法和谐波叠加法分别模拟得到随机轨道不平顺激励样本和风速时程样本,并将所获得的双重随机荷载引入车辆‑轨道耦合振动系统中求得代表性响应;采用双边差分法求解所建立的代表性响应的概率密度演化方程,获得振动响应的时变概率密度演化分布,并采用蒙特卡罗法(MCM)验证本文模型的计算效率和精度。研究结果表明:概率密度演化方法(PDEM)适用于横风和轨道不平顺双重随机激励作用下的车辆‑轨道系统随机分析,且对于本文模型,当代表性样本点数为300,筛选半径取17.7时能够达到良好的计算效果;仅在单重随机荷载作用下进行随机响应分析不能准确反映车辆‑轨道系统的随机动力特性,论证了开展双重随机激励作用下车辆‑轨道系统随机分析的必要性。

     

    Abstract: Based on the train-track coupling dynamics and probability density evolution theory, a random vibration model of train-track system considering both the crosswind and track irregularity is established. The N-dimensional hypercube point set is used to generate the discrete random frequency and phase representative point set. Based on the random harmonic function method and the harmonic superposition method, the random track irregularity excitation samples and the wind speed time-history samples are simulated respectively. The obtained two random excitations are introduced into the train-track coupling system to obtain the representative responses. The probability density evolution equation of representative response is solved using the bilateral difference method to obtain the time-varying probability density evolution distribution of the vibration response. The Monte Carlo method (MCM) is employed to verify the computational efficiency and accuracy of the proposed model. The results indicate that the probability density evolution method (PDEM) is appliable to the random analysis of vehicle-track system under double random excitations including crosswind and track irregularity. When the number of representative sample points is 300 and the screening radius is 17.7, a good calculation results can be obtained by the proposed model in this paper. The random response analysis regarding a single random input cannot express an accurate result of the vehicle-track system’s random dynamic characteristic, which indicates the required consideration of both random excitations of crosswind and track irregularity in the random vibration analysis of vehicle-track system.

     

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