High-Cycle Fatigue Strength Prediction Model for Ti-6Al-4V Titanium Alloy Compressor Blades Subjected to Foreign Object Damage

The high-cycle fatigue (HCF) strength of titanium alloy blades, particularly Ti-6Al-4V, is critical for the reliability and performance of aviation engine components. Foreign object damage (FOD), which introduces notches, microstructural alterations, and residual stresses, significantly degrades the fatigue performance of these blades. Of particular concern are tensile residual stresses, which, caused by factors such as FOD, notches, or non-uniform plastic deformation, lead to increased local tensile loads, promote crack initiation, and accelerate crack growth. This study investigates the effects of external damage, including the impact angle and the resultant residual stresses, on the high-cycle fatigue strength of Ti-6Al-4V titanium alloy blades. Blade simulation specimens with impact-induced damage were tested under high-cycle fatigue conditions to assess the influence of various impact angles and the resulting tensile residual stresses. A modified fatigue strength prediction model was developed, incorporating shear factors and tensile residual stresses, to improve the accuracy of fatigue life predictions. Compared with the Neuber model and Peterson model, the modified model increases the proportion of predictions falling within the 10% scatter band by 30%, resulting in a significant improvement in prediction accuracy. The experimental results demonstrated that the modified model more accurately predicted the high-cycle fatigue strength, particularly in the presence of external damage and tensile residual stresses.