Pitting corrosion notably increases stress concentration, thus accelerating fatigue crack initiation and propagation at the pit base. This research quantifies the relationship between pit dimensions and fatigue crack development by introducing crack extension ratios (​ and )​. Employing a series of finite element models, the influence of pit characteristics on the stress intensity factor () at the crack tip is assessed. Based on these assessments, a formula for computing the -value is proposed. Furthermore, a two-stage fatigue life prediction model for both partial and complete penetration is developed using the Paris equation. Results indicate that pits substantially affect the -value during partial penetration. Specifically, as approaches zero, the -value approaches zero, and as approaches one, it aligns with the -value of a semi-elliptical surface crack. Conversely, in the complete penetration phase, the influence of the pit on the -value is negligible, and the -value can be calculated according to the plate with a central penetrating crack. Experimental validation confirms that the model generally maintains a prediction error within 10%.

中文翻译：

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考虑凹坑特性的腐蚀钢板疲劳裂纹扩展寿命预测模型


点蚀显着增加应力集中，从而加速疲劳裂纹在坑底的萌生和扩展。这项研究通过引入裂纹扩展比（​和）​来量化凹坑尺寸和疲劳裂纹发展之间的关系。采用一系列有限元模型，评估凹坑特征对裂纹尖端应力强度因子（）的影响。基于这些评估，提出了计算 值的公式。此外，使用巴黎方程开发了部分和完全穿透的两阶段疲劳寿命预测模型。结果表明，凹坑显着影响部分穿透过程中的 β 值。具体来说，当接近零时， - 值接近零，而当接近一时，它与半椭圆形表面裂纹的 - 值一致。反之，在完全焊透阶段，凹坑对β值的影响可以忽略不计，β值可以根据有中心贯穿裂纹的板材计算。实验验证证实该模型总体预测误差保持在10%以内。