Abstract To increase the prediction accuracy of small-number sample life data, improved backward statistical inference approach (ISIA) was formulated using the modified distribution coefficients while fitting the fatigue probabilistic S-N (P-S-N) curve. Based on the search path searching for fatigue parameters, the novel scheme captures the optimal coefficients that can efficiently correlate the life distribution and stress levels. The equivalent lives can be obtained through the conversion of fatigue life to the highest stress level. To acquire a realistic P-S-N curve of full-scale components, the life distribution effect of small-number samples can be considered when fitting curves. Results show that for a set of data with an accurate standard deviation at the first stress level, the predicted lifetime using the ISIA is approximately 8.7% of the conventional group method and is only 10.5% of the original backwards statistical inference method. Meanwhile, by comparing the predicted results with the fatigue life testing data of full-scale alloy steel EA4T axles, the accuracy of fatigue P-S-N curves by using ISIA is further confirmed. For the modern axle materials and welded structures widely used in railway vehicles, the newly-proposed ISIA can not only achieve a reliable fatigue life, particularly in the high cycle fatigue regime, but also provide a more conservative fatigue P-S-N curve than traditional fitting methods.

中文翻译：

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疲劳 PSN 曲线的确定 - 批判性审查和改进的后向统计推断方法

摘要 为了提高小样本寿命数据的预测精度，在拟合疲劳概率SN（PSN）曲线的同时，利用修正后的分布系数制定了改进后向统计推断方法（ISIA）。基于搜索疲劳参数的搜索路径，新方案捕获了可以有效关联寿命分布和应力水平的最佳系数。等效寿命可以通过将疲劳寿命转换为最高应力水平来获得。为获得逼真的全尺寸元件PSN曲线，拟合曲线时可考虑小样本的寿命分布效应。结果表明，对于在第一应力水平具有准确标准偏差的一组数据，使用 ISIA 的预测寿命约为 8。7%的常规分组方法，仅是原始反向统计推断方法的10.5%。同时，通过将预测结果与全尺寸合金钢EA4T车轴疲劳寿命测试数据进行对比，进一步验证了ISIA疲劳PSN曲线的准确性。对于铁路车辆广泛使用的现代车轴材料和焊接结构，新提出的 ISIA 不仅可以实现可靠的疲劳寿命，特别是在高周疲劳状态下，而且可以提供比传统拟合方法更保守的疲劳 PSN 曲线。进一步证实了使用ISIA的疲劳PSN曲线的准确性。对于铁路车辆广泛使用的现代车轴材料和焊接结构，新提出的 ISIA 不仅可以实现可靠的疲劳寿命，特别是在高周疲劳状态下，而且可以提供比传统拟合方法更保守的疲劳 PSN 曲线。进一步证实了使用ISIA的疲劳PSN曲线的准确性。对于铁路车辆广泛使用的现代车轴材料和焊接结构，新提出的 ISIA 不仅可以实现可靠的疲劳寿命，特别是在高周疲劳状态下，而且可以提供比传统拟合方法更保守的疲劳 PSN 曲线。