Vibration Analysis of a Multi-disk, Bearing and Mass Unbalance Rotor Using Assumed Modes Method

This paper aims to presents a simple and efficient approach for modelling and solving the equations of a rotor with any number of disks, bearings and mass unbalances using the assumed modes method. This model consists of a continuous shaft, arbitrary number of mass unbalances in any axial location and phase angle, and any number of rigid disks and bearings. This arrangement is extensively used in diverse applications. In this study, final governing differential equations are not derived because the assumed modes method is directly inserted into solving process. Some examples in both cases of free and forced vibration have been dealt with. The results show the accuracy of this approach and its prediction of vibration behaviour of the rotor in a complex combination of shaft, disk and bearing. This study also shows the results are as accurate as the results of the most popular approach, i.e. the Finite Element Method.