Unbalance response of rotors: A modal approach with some extensions to damped natural systems
Abstract
A modal procedure for the computation of the unbalance response of rotors modelled as systems with many degrees of freedom (possibly by using the finite element method) is suggested. If damping is neglected, the procedure is quite similar to that usually followed for a nonrotating structure, the only difference being the possibility of obtaining also modes with negative modal masses which cannot in general be neglected. Following a similar procedure damped systems can be also studied; if the distribution of damping is not "proportional", an iterative approach that is costeffective from the computational point of view is suggested both for natural and nonnatural systems. The modal procedure is extended also to the case of nonisotropic machines with a nonsymmetric stator or nonsymmetric rotor. A computational procedure which can be used for the computation of the "backbone" and the stable branches of the response of nonlinear systems is shown. An example of application to a rotor with many degrees of freedom is also reported.
 Publication:

Journal of Sound Vibration
 Pub Date:
 July 1990
 DOI:
 10.1016/0022460X(90)90911I
 Bibcode:
 1990JSV...140..129G