基于核密度估计的履带车辆传动轴载荷谱编制

Load Spectrum Compiling for Transmission Shaft of Tracked Vehicle Based on Kernel Density Estimation

为了建立军用履带车辆传动轴典型路面上的高可靠性载荷谱,通过实车试验采集接近实际使用情况的扭矩载荷及相关行车数据,由最少测试次数判据计算出载荷数据样本的置信度。由于试验载荷数据具有不规则的均幅值二维分布,基于二维核密度估计设计编谱流程,采取2次雨流计数,第1次雨流计数结果用于均幅值极值推断,第2次雨流计数结果用于核密度估计,既能很好地拟合均幅值分布,又能对实测雨流矩阵做合理外推。在获得典型路面使用寿命里程的二维设计载荷谱后,通过等损伤转换方法,将二维谱转化为以幅值为变量的8级程序块谱,并给出传动轴扭矩和转速的联合加载方法。研究结果表明,从疲劳损伤角度选择低载,舍去阈值为第8级幅值的0.8倍,频次和减少99.33%而损伤和只减少0.29%,可加速疲劳加载试验。

For establishing the high reliability load spectrum for transmission shaft of military tracked vehicle on the typical road,the torque and relevant vehicle data similar to that in real service conditions was collected through vehicle experiments,and the confidence level of load data samples was calculated based on the criteria of least testing times. A load spectrum compiling procedure is designed based on 2-D kernel density estimation on account of the irregular 2-D distribution of amplitude and mean values in test load data. In the load spectrum compiling procedure,two times of rain-flow counting are adopted： the first rain-flow counting result is used to deduce the extrema of amplitude and mean values,and the second rain-flow counting result is used to extrapolate the kernel density. This compiling procedure can not only obtain better fitting of amplitude and mean distribution,but also achieve the reasonable extrapolation of the experimental rain-flow matrix. Goodman equation and the equivalent damage conversion method are used to derive 8-level program block load spectrum from 2-D load spectrum,and a loading method for the combination of torque and rotational speed is presented. 0. 8 times of eighth amplitude are chosen as the value of small load from the perspective of fatigue damage,and total cycles are decreased by 99. 33% while total damage is decreased only by 0. 29%,which can accelerate the fatigue loading test.