A New Method of Calculating Transient Response of Complex Rotors

In this paper the ‘transfer coefficient-direct integral method’ is developed to analysis of transient response of rotor systems, especially for non-linear rotor systems. The main difference from the classical transfer matrix-direct integral method rests with the introduction of complex modal analysis corresponding to positive and negative whirling frequencies, and after obtaining the critical speed and the corresponding vibration modes by the transfer coefficient method it is no longer necessary to do transfer calculation (but in classical transfer matrix-direct integral method, after every integral step, it is necessary to do a transfer calculation through the whole rotor system). In the transfer coefficient-direct integral method, corresponding every integral step it is only a linear transformation between the real displacements and the modal displacements. It makes the transfer calculation and the direct integral become two independent steps of the calculation. Each step fully takes advantages of the method correspondent. The whole analysis procedure is then greatly simplified. The paper gives, at first, the principle of the transfer coefficient-direct integral method. After this, the transient response of a co-axial double rotor system with a squeeze film damper is calculated by the method. The response history of the system from an initial time to stable state is given.