基于超高周疲劳多元化失效模式的概率S-N曲线模型构建方法

A METHOD TO BUILDING PROBABILISTIC S-N CURVES FOR MULTIPLE FALIURE MODES IN VERY HIGH CYCLE FATIGUE

  • 摘要: 对渗碳CrMn钢开展了超高周疲劳试验,通过观察断口发现其失效模式分为表面裂纹诱发失效、内部夹杂导致的高周疲劳(5×104<N<107)失效以及超高周疲劳(N>107)失效三种。该文假设每一种失效模式的S-N曲线均相互独立,并基于混合Weibull分布以及Basquin和三参数S-N曲线模型,分别构建出了渗碳CrMn钢三种失效模式各自的概率S-N曲线及综合反映渗碳CrMn钢多元化失效模式的概率S-N曲线。与试验数据相比,99%存活概率的P-S-N曲线在超长寿命区给出了较为安全的寿命预测。

     

    Abstract: Very high cycle fatigue (VHCF) tests were carried out by using the carburized CrMn steel. By observing the fracture surface, three different failure modes were distinguished, namely the surface-crack induced failure mode and the inclusion induced failure mode under HCF (5×104<N<107) and VHCF (N>107) conditions. The S-N curves were assumed for each failure mode in the present study. Based on the mixed Weibull distribution, the Basquin S-N curve and the three-parameter S-N curve, the probabilistic S-N (P-S-N) curves were established for three different failure modes respectively, and a method for constructing the P-S-N curve associated with multiple failure modes was developed. In comparison with experimental data, the fatigue life predicted by the P-S-N curve with 99% survival probability is acceptable at VHCF regime.

     

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