Modal analysis of rotors under special support conditions

Gyroscopic rotors in rolling element or tilting pad bearings assume a particular model structure if bearing load directions coincide. For simple bearing models in suitable coordinates, stiffness and damping matrix are free from cross-coupling terms. Under these conditions, a relationship between right and left eigenvectors is derived. The rows of the frequency response matrix are related to its columns, and the elements of the frequency response matrix are expressed in terms of eigenvalues and right eigenvectors. The results are illustrated by a numerical example. The theory can be used to facilitate advanced applications of modal testing for a special class of rotors.