腐蚀结构损伤评估方法

针对腐蚀环境下老龄化飞机结构表面存在广布随机的腐蚀坑,而使其强度降低这一问题,先采用有限元方法并结合仿真软件ANSYS的参数化分析语言APDL,得到不同形状腐蚀坑底部的有效应力集中系数,然后结合局部应力应变法求解各个腐蚀坑底部在疲劳载荷作用下产生初始裂纹的萌生寿命值,再通过蒙特卡罗方法求解数值积分和非线性方程,得到和腐蚀坑具有相同寿命等效裂纹的尺寸,最后采用神经网络技术建立腐蚀坑各种几何尺寸与等效裂纹深度间的多变量非线性映射关系.为工程实践中用广布裂纹方法处理含随机分布腐蚀坑的老龄化结构提供可能.

DAMAGE ASSESSMENT TECHNIQUES FOR CORRODED STRUCTURES

The widespread stochastic corrosion pits with different radii on structural surface cause structural strength reduction in evaluation analysis of aging aircrafts under corrosive environment. The finite element method and APDL language of ANSYS are used to obtain the effective stress concentration factor at the bottom of different shaped pits bottom through parametric analysis. And then the method of local stress and strain are used to solve the crack initiation lives under fatigue loads for all pits. Based on the crack initiation lives,the equivalent initial surface crack sizes are calculated through reverse integration of the Paris fatigue crack growth law combined with Monte Carlo method to solve non-linear equation. Finally the nonlinear relation between sizes of pits and equivalent initial surface crack is set up through neural network technology. The work provides theoretical reference for analysis of the damage structure with cor- rosion pits treated as widespread cracks in engineering practice.