Methodology for Predicting the Fatigue Life of TC4 Alloy with Corrosion Pit Based on Nonlinear Ultrasonic Evaluation

A fatigue life prediction method for corrosion pits was developed by integrating continuum damage mechanics with nonlinear ultrasonic techniques. Fatigue tests were conducted on TC4 compressor blade specimens with prefabricated corrosion pits to provide experimental data for model development. Three nonlinear ultrasonic approaches were investigated through both numerical simulations and experimental validations to evaluate their sensitivity to corrosion-induced damage. The results indicate that pit size significantly influences fatigue life and crack initiation behavior. Three nonlinear ultrasonic techniques effectively characterized the damage caused by corrosion pits, with the nonlinear acoustic parameter technology exhibiting the highest sensitivity. All life prediction results by nonlinear ultrasonic wave parameters falling within the factor-of-2 scatter band, with the model using nonlinear acoustic parameters showing the best performance. These findings demonstrate the potential of nonlinear ultrasonics technology for effective characterization and life assessment of corrosion pit damage.