Experimental validation of modal parameters in rotating machinery

Abstract

In this paper, instability of rotating machinery systems due to rotating damping is investigated through experimental modal analysis. Generally, advanced methods are needed for these kind of systems because of the asymmetry of the matrices. However, it is shown by means of cyclic energy dissipation that the rotating damping can be handled as damping which changes due to the rotating speed. The use of damping matrix estimation techniques is discussed and a method is proposed to estimate and model the influence of the rotating damping matrix. A dedicated experimental setup, with negligible gyroscopic effect, is presented for validation purposes. It is shown experimentally that the estimation of the rotating damping matrix is able to predict the decay rate of the first forward mode.