腐蚀疲劳裂纹扩展与寿命估算

CRACK PROPAGATION AND LIFE PREDICTION UNDER CORROSION FATIGUE

将有效的疲劳裂纹扩展速率表达式应用于腐蚀疲劳,对腐蚀疲劳裂纹扩展寿命估算进行了初步探讨。结果表明:腐蚀疲劳裂纹扩展速率(da/dN)_(CF)与(△K-△K_(thCF))在双对数坐标上呈线性关系。首次提出临界加载频率概念,频率高于临界加载频率,频率对裂纹扩展没有影响;频率低于临界加载频率,提出了表示频率对裂纹扩展速率影响的频率效应函数。经客观的验证,用文中提出的公式估算的腐蚀疲劳裂纹扩展寿命和实验寿命吻合良好。

A study on the prediction of corrosion fatigue life has been carried out by applying the crack propagation rate formula for fatigue to corrosion fatigue. It results in that the crack propagation rate, (da / dN)CF, has a linear relationship with (ΔK - ΔKthCF) on double-Log plots. The concept of critical loading frequency,fc, has been put forward. When Loading frequency f≥fc , the frequency has no effect on (da / dN)CF. When f<fc, a frequency affecting function is drawn into the crack propagation rate formula. By objective verification, the predicting life agrees with the testing life. This method can hopefully be applied to predict corrosion fatigue crack propagation life in engineering structures.