基于应力强度干涉模型的疲劳损伤

Fatigue damage based on the mathematic model of stress interference

基于Miner法则,分析了阶梯谱级数对疲劳寿命精度的影响.建立了变换的S-N曲线与阶梯谱拟合曲线的应力强度干涉数学模型,采用参数求解的数值解析法,得到参数并推导出了疲劳损伤的积分公式.对铁路货车转向架侧架运行36万km(一个段修期)内,分阶段的多次载荷谱测试数据进行分析,发现随着各阶段阶梯谱离散级数的增大,损伤成收敛趋势,寿命预测精度提高.采用本文的分析方法,建立了侧架一个段修期的载荷谱概率模型,可预测侧架的寿命及可靠性.

According to the Miner principle, the influence of ladder spectrum which was usually used in valuation of fatigue life was analyzed. The stress interference of mathematic model of transform S-N curve and fitting curve of ladder spectrum was founded. The parameter was gained by using numerical analytic method, and the integrabel formula of fatigue damage was derived. The test data of many load spectrums which were got form side bearer of bogie with in 360 000 kilometers （a segment fix period） were analyzed, and the rule of convergence trend about the ladder of load spectrum and fatigue was founded, and the fatigue life was estimated more accurately. Using the method mentioned in this paper, one probability model of ladder spectrum about side of bogie was established, and the reliability of fatigue life about the side of bogie was estimated.