基于蚀坑形貌特征的2198-T8铝锂合金预腐蚀疲劳寿命预测

Pre-corrosion Fatigue Life Prediction of 2198-T8 Aluminum-Lithium Alloy Based on Morphological Characteristics of Corrosion Pits

通过盐雾环境条件下的预腐蚀疲劳试验测试2198-T8铝锂合金的疲劳寿命,并基于蚀坑形貌对腐蚀疲劳寿命进行了预测。结果表明,在同一腐蚀环境参数下,蚀坑的长度、宽度及深度均满足对数正态分布。将蚀坑形貌简化为半椭球状的几何模型,与试验寿命数据相结合,通过ABAQUS有限元模拟、数字图像相关裂纹监控技术和理论计算,得到蚀坑深度与等效初始裂纹长度之间的等价关系,最后使用Paris公式对不同参数下的预腐蚀疲劳试样进行寿命预测,预测结果均处于1.5倍分散带以内。

The fatigue life of 2198-T8 aluminum-lithium alloy was tested by the pre-corrosion fatigue test under a salt spray environment,and the corrosion fatigue life was predicted based on the morphology of corrosion pits.The results show that under the same corrosion environment parameters,the length,width and depth of the pits all satisfy the log-normal distribution.The pit shape was simplified into a semi-ellipsoidal geometric model,combined with the test life data;through ABAQUS finite element simulation,digital image correlation crack monitoring technology and theoretical calculations,the equivalent between the pit depth and the equivalent initial crack length was obtained.Finally,the Paris formula is used to predict the life of the pre-corroded fatigue specimens under different parameters,and the prediction results are all within 1.5 times the dispersion zone.