Flexural vibration of rotating shafts by frequency domain hybrid modelling

In this paper the flexural vibration of a cantilevered rotating marine propeller is considered. From the transfer matrices of the distributed shaft and the lumped disc model, characteristic determinant of the distributed-lumped model of the system is derived. Direct search optimisation techniques are employed, enabling complex roots of the irrational characteristic determinant to be determined. Frequency response methods are used to determine the flexural response of the system. The discrete inverse Fourier transform technique is employed to compute the transient response from the frequency response data. Both the resonance and gyroscopic effects are identified. It is shown that by using frequency domain hybrid techniques, the system could be represented accurately by a reduced order model.