Failure and Risk Analysis of Aeroengine Turbine Rotor Blade Fractured Due to Arch Binding

This study investigated the failure mechanism of the first-stage turbine rotor blades in a CT7 engine. Metallurgical analysis ruled out the possibility of failure due to the inherent properties of the blade material. A finite-element analysis (FEA) model for the blade was constructed based on computed tomography images. Thermomechanical FEA showed an increase in maximum principal stress on the failure region up to 17% when arch binding occurred. Moreover, a vibration mode analysis indicated that the natural frequency increased with the operational frequency. Based on a risk assessment considering the occurrence of failure, the risk index increased exponentially with the blade replacement interval. Thus, a replacement interval of 5600 engine flying hours is suggested to maintain the risk level within the safe threshold.