车桥竖向随机振动的概率密度演化分析

来源期刊:中南大学学报(自然科学版)2015年第4期

论文作者:毛建锋 余志武 谈遂 曾志平

文章页码:1420 - 1428

关键词:车桥耦合模型;概率密度演化方法;轨道高低不平顺;N维超立方体点集;功率谱

Key words:train-bridge system model; probability density evolution method; vertical track irregularity; N-dimensional hypercube point set; power spectrum

摘    要:基于车-桥竖向耦合模型,引入不平顺功率谱随机谐和函数,采用N维超立方体点集(gp集)选取离散随机频率代表点,得到代表性轨道高低不平顺随机激励样本并进行慢变调制;建立概率密度演化方法的随机动力方程,基于MATLAB编制车桥耦合随机振动概率密度演化分析程序;采用newmark-β积分法及带TVD格式的双边差分法计算车桥振动响应的均值、标准差及时变概率密度演化分布。研究结果表明:与Monte Carlo法相比,概率密度演化法分析车桥随机振动精度更高,计算效率提高1~2个数量级;输入均匀随机分布频率和初相位的轨道不平顺激励,输出响应并非均匀分布,随车速先增加后减少,概率分布呈高斯型分布;轨道不平顺引起的系统随机响应受车速影响较大。

Abstract: Based on the simple vertical model of the train-bridge system, the random harmonic functions of track vertical irregularity power spectrum were introduced. The representative points of random frequency were selected by utilizing the N-dimensional hypercube point set method, which formed the sample of random excitation modulated by the slowly varying function. The random dynamic equation for probability density evolution method was formulated, and by using MATLAB, program for the probability density evolution and analysis of train-bridge coupled random vibration were developed. Eventually, newmark-β integration method and double edge difference method of TVD format were adopted to obtain the mean value, the standard deviation and the distribution of the time dependent probability density evolution. The results show that compared to the Monte Carlo method, the probability density evolution method has higher accuracy and computation efficiency, with efficiency improved by 1-2 order of magnitudes. When the excitation with randomly distributed frequency and initial phrase for track vertical irregularity is input, the output is not uniformly distributed, rather it distributes in Gaussian style, i.e., with the increase of train speed, the response of system firstly increases and then decreases. The random system response incurred by track vertical irregularity is significantly influenced by trains speed.

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