Fretting wear and vibration fatigue behavior of a Ti-6Al-4V fan blade dovetail assembly subjected to resonant vibration

Dovetail assemblies are widely used in aero engine fan blades. During engine operation, these structures are prone to vibration-induced fretting wear, which can significantly impair their service reliability. To address this issue, Ti-6Al-4V fan blades manufactured based on a real engineering structure were employed, and systematic investigations were carried out using a self-developed vibration test platform to study the fretting wear and vibration fatigue in dovetail assemblies under resonant vibration conditions. First, the effects of clamping degree and external excitation load amplitude on the vibration response characteristics and contact states of the blade under resonance were analyzed. Subsequently, vibration fatigue tests with up to 3 × 10⁷ cycles were conducted at the first order resonant frequency to examine the evolution of fretting wear morphology and wear depth on the dovetail tenon contact surface at different numbers of cycles. The results indicate that a reduction in the clamping force level leads to a decrease in interfacial contact stiffness, causing the resonance peak to shift toward lower frequencies. As a result, the displacement amplitude response increases significantly, whereas the strain in the blade body shows only minor variation. With increasing excitation load, both displacement and strain responses are markedly enhanced, accompanied by aggravated contact surface wear exhibiting pronounced asymmetry. On this basis, a prediction model for the average surface wear depth in the dovetail tenon contact zone was established based on energy dissipation theory, and the predictive accuracy of the model was validated against the experimental results.