Dynamic Response of Rotors Using Modal Reduction Techniques

A modal reduction technique is discussed and proposed for solving rotor-dynamic problems. The component mode method is used to model a rotor shaft, and the resulting system matrices are reduced in size by considering only the contribution of the more important lower modes. The final system response including the bearing and disk is obtained using complex modal analysis. Since the higher modes do not contribute significantly to the system response, this method is found to be computationally economical. Unbalance response analyses of a simple Jeffcott rotor obtained by experiments are compared with those obtained by the modal reduction technique and show strong agreement.