采用等效载荷的装甲车辆扭力轴疲劳可靠性评估

Fatigue Reliability Modelling and Evaluation of Torsion Shaft for Armored Vehicles Using Equivalent Load Spectrum

为了评估扭力轴在随机载荷作用下的动态疲劳可靠性,提出了一种基于疲劳可靠性异量纲干涉模型的扭力轴动态疲劳可靠性评估方法。将实测扭力轴载荷频次谱进行分布拟合,生成随机载荷历程,利用雨流计数法获得载荷幅值、均值和循环次数,经平均应力修正后统计极值载荷分布,构建等效输入应力谱,避免了多次载荷等效的统计分析;基于材料P-S-N曲线,应用样本集聚原理建立疲劳寿命概率分布连续模型,实现变幅应力疲劳寿命的连续表达。对某扭力轴疲劳可靠度的分析结果表明:在寿命为15×10^4 km时,计算的扭力轴疲劳可靠度与文献方法计算结果相对误差小于2%,扭力轴疲劳可靠度的50次和10000次仿真结果的变异系数均小于1%。

To evaluate the dynamic fatigue reliability of a torsion shaft under random loads,an evaluation method for the dynamic fatigue reliability of torsion shaft is proposed based on the dissimilar-dimension interference model of fatigue reliability.The measured load frequency spectrum of a torsion shaft is analyzed and the probability distribution is fitted.The random load spectrum is obtained using the probability distribution of load.The amplitude,mean value and number of cycles are obtained using the rainflow counting method.The equivalent stress spectrum is obtained by the statistic extreme load after amending mean stress.Therefore,frequent statistical analysis of equivalent constant load is avoided.A continuous model of probability distribution of fatigue life is established following the principle of sample concentration and P-S-N curves of material.The expression of fatigue life under variable amplitude stress is obtained.The reliability analysis of a torsion shaft shows that the reliability difference between the proposed method and a reference method is less than 2%.The variation coefficient is less than 1%through statistical analysis on the results obtained by multiple simulations under random loads.