预腐蚀结构耐久性分析的概率断裂力学方法

PROBABILISTIC FRACTURE MECHANICS APPROACH FOR DURABILITY ANALYSIS ON PRE-CORROSION STRUCTURES

考虑腐蚀环境的影响,建立了预腐蚀后结构耐久性分析的概率断裂力学方法。预腐蚀疲劳是影响飞机结构经济性和安全性的最重要因素,考虑地面停放预腐蚀的影响,建立预腐蚀条件下的相对小裂纹扩展规律,以裂纹萌生寿命(TTCI)服从双参数威布尔分布和对数正态分布为基础,反推得到预腐蚀条件下的当量初始缺陷尺寸分布(EIFSD),从而得到任意时刻裂纹尺寸分布函数,进行损伤度分析和经济寿命预测,并进行了预腐蚀后的某型飞机机翼副梁的经济寿命评定。

To predict the economical life for pre-corrosion structures, the probabilistic fracture mechanics approach （PFMA） under pre-corrosion environment is presented. The economics and safety of structures are influenced seriously by pre-corrosion fatigue. Based on the principle of PFMA in laboratory environment, the crack growth rule is founded accounting for the pre-corrosion on the ground and corrosion fatigue in the air. While the time to crack initiation （TTCI） is assumed to follow the two-parameter Weibull or logarithmic normal distribution, the equivalent initial flaw size distribution （EIFSD） is back-deduced under pre-corrosion environment. Thusly, the crack size distribution is gained, the damage degree is evaluated and the economical life is predicted. This approach can be applied in evaluating the economical life for pre-corrosion aircraft wing joints successfully.