Fracture Analysis of Centrifugal Impeller Blade of Gas Turbine Starter

During the long test to a certain stage of gas turbine starter, the decomposition inspecting findings that the exhaust edge blade of centrifugal impeller was fractured. Though the analysis of macro and micro observation, microstructure examination, organization inspection, hardness testing on fracture surface. The result shows that the nature of centrifugal impeller blade fracture was high cycle fatigue, it may be related to disc vibration. Calculated the frequencies of centrifugal impeller at different rotational speed as well as the camp bell diagram were worked out. The centrifugal impeller has high frequency coupling resonance near the design point, strong excitation load, the combined action of two causes result the blades fracture.