The impact of random loading on the fatigue life of mechanical components contains numerous uncertainties. This study aims to enhance the precision of life prediction by developing mean and amplitude distribution models based on the road load spectrum and extrapolating the operational load beyond the threshold value in the time domain. Additionally, it considers the influence of high cycle fatigue (HCF) and low cycle fatigue (LCF) loads on the initiation life of metal cracks. To address this, a load correction factor is introduced, and critical stresses for high and low cycle loads are proposed. Furthermore, a two-dimensional programmed load spectrum is prepared, taking into account the mean and amplitude. The accuracy and rationality of the fatigue life model are validated through examples using 45# steel and 316L, while experiments on engine support are conducted to confirm the effectiveness and accuracy of the over-threshold extrapolation life prediction method under random loading.

中文翻译：

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基于载荷谱外推的随机载荷下金属材料疲劳寿命预测


随机载荷对机械部件疲劳寿命的影响包含许多不确定性。本研究旨在通过开发基于道路载荷谱的平均值和幅度分布模型并在时域中推断超出阈值的运行载荷来提高寿命预测的精度。此外，它还考虑了高周疲劳（HCF）和低周疲劳（LCF）载荷对金属裂纹萌生寿命的影响。为了解决这个问题，引入了载荷修正系数，并提出了高循环载荷和低循环载荷的临界应力。此外，考虑平均值和振幅，准备二维编程载荷谱。通过45#钢和316L的实例验证了疲劳寿命模型的准确性和合理性，并通过发动机支架实验验证了随机载荷下超阈值外推寿命预测方法的有效性和准确性。