基于非线性超声检测信号的结构件腐蚀疲劳剩余寿命评估方法

A life assessment method based on nonlinear ultrasonic detection signals was proposed for blade structures with corrosion defects. The finite element method was used to simulate the ultrasonic non-destructive testing process of the corrosion defect specimens， the influence of corrosion pits on nonlinear coefficient and maximum stress was explored. Then， by establishing a fatigue life prediction model of a single corrosion pit test piece， a fatigue life assessment method for blade structures with corrosion pits based on nonlinear ultrasound was proposed. Taking a compressor blade as an example，the detailed process of the assessment method was introduced， and the feasibility was verified. The results showed that the corrosion pit diameter was positively correlated with the nonlinear coefficient. Under the same corrosion conditions，changes in the maximum stress and nonlinear parameter were consistent. The life prediction results of specimens with single corrosion pit fell in the factor of two scatter band，and the error range of life prediction results of blade structure with corrosion pits was within 25%. The study showed that the nonlinear coefficient could characterize the damage caused by corrosion pits effectively，and the nonlinear ultrasonic detection methodology could provide a feasible means for fatigue life assessment of blade structures with corrosion pits.