Phase Tangent Slope Method for Modal Damping Identification of a Simulation Power Turbine Rotor

摘要

Aiming at the problem that modal damping of mechanical system is difficult to be identified accurately, and then a method called phase tangent slope method was presented. The method is utilized amplitude-frequency and phase-frequency curves of vibration response data, and then modal damping ratio is indirectly gained through calculating the phase tangent slope at the resonance point. The method was applied in simulation analysis and experimental verification and compared with the half-power bandwidth method, and the results demonstrated that the calculated modal damping ratio in the simulation analysis is very close to the theoretical value, and the maximum error of the two method is less than 0.06%. In the modal damping identification of the real rotor, the mean values of the identified modal damping ratios in the two directions have the same order of magnitudes, and their relative error is 7.18%. which further validates the correctness of the method.