二维随机载荷作用下汽车螺旋弹簧疲劳损伤研究

Research on Fatigue Damage of Automobile Coil Springs under Actions of Two Demensional Random Loads

提出了二维随机载荷谱外推的三种方法;对幅值服从形状参数α=1、位置参数ε=0的威布尔分布和均值服从正态分布的二维随机载荷的当量载荷的概率密度函数进行了推导,给出了概率密度函数的数学模型。以一款城市SUV为研究对象,采集试验场强化路面的载荷谱数据,提出了采用样本截断方法进行随机载荷谱参数估计的方法。参数检验结果表明,在中高载荷段,采用该方法可以很好地实现对所采集的载荷谱数据的拟合。采用载荷谱分级法对所采集的二维随机载荷进行外推,基于外推的载荷谱对疲劳损伤进行计算分析,研究了不同的载荷分级方法对疲劳损伤计算结果的影响。研究结果表明,当载荷谱幅值分级小于20级时,损伤计算会有较大误差,出现偏小的结果,载荷均值的分级影响相对要小于幅值的分级影响。

The expandation of two dimensional random load spectrums was researched,three expandation methods were presented.The probability density function of equivalent loads of two-dimensional random loads were deduced,as the mean loads of the two-dimensional random loads following Gaussian distribution,and the amplitude following Weibull distribution under the conditions of shape parameterα=1 and dimensional parameterε=0,the math models of the probability density functions were presented.Take a city sport utility vehicle(SUV)as object,the load spectrum data on reinforced pavement was aquired in test ground.Sample interception method was presented for parameter estimation of radom loads.Parameter checking shows that the method may realize a good fitting on middle and high load regions.The acquired two dimensional random loads were expanded by load date segmentation method.Fatigue damage was analyzed under the expandation loads.The influences of different segmentation methods on the result of fatigue damage calculation was studined.The results show,when the segments of amplitude is less than 20,the fatigue damage will be high deviation to a smaller result,and the influences of the segment number of mean loads will be less that of the segment number of amplitudes.