OPERATIONAL MODAL ANALYSIS FOR ROTATING MACHINES: CHALLENGES AND SOLUTIONS

Operational Modal Analysis (OMA) is widely employed and became an industrial standard technique for identifying the modal parameters (i.e. resonance frequencies, damping ratios and mode shapes) of mechanical structures. Several hypothesis need to be verified in order to apply OMA. First of all the structure must be Linear Time Invariant (LTI), but this is not the case if several parts are moving with respect to each other. Secondly, the forces acting on the structure must be represented by white noise in the frequency range of interest. This is not valid anymore if periodical loads due to rotating elements are introduced in the system. The main scope of this paper is to fully understand and propose solutions to the challenges and the limitations occurring when applying classical OMA techniques in case of rotating machines.