A finite element analysis(FEA)method was adopted to calculate the modes and static stress generated from centrifugal force of the impeller blades and a unidirectional coupled fluid-structure interaction method was applied to analyze the forced vibration of the impeller blade on excitation of the unsteady aerodynamic loads. In order to save the computational cost
the centrifugal impeller was modeled as a single sector based on the cycle symmetry assumption. The result shows that the insufficient margin between the dominant frequency of unsteady aerodynamic loads and the 6th natural frequency of the impeller blade results in local resonance vibration at the leading edge of the impeller blade. Although the equivalent stress is lower than the yield stress of steel
the high cycle fatigue(HCF)failure of the impeller blade may be caused by the long-term excitation of the unsteady aerodynamic loads. The predicted stress concentration region of the impeller blades is in accordance with the actual crack location.
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