Experimental evaluation of a modal parameter based foundation identification procedure

Abstract

One approach to model foundations of existing turbomachinery installations uses motion measurements at bearing supports and at select points on the foundation to identify the modal parameters of an equivalent foundation. This paper describes an experimental evaluation of this approach. Discussed are the experimental rig, its commissioning, the procedure for obtaining the required measurements and preliminary identification results. The proposed approach could identify reasonably accurately foundation natural frequencies, but identification of damping ratios, modal masses and mode shapes was significantly influenced by input data errors. The resulting equivalent foundation could predict only approximately the frequency response of the rig. Further investigations are needed to improve these predictions prior to field applications.