Component mode synthesis using experimental modes enhanced by mass loading

Abstract

A technique is presented for synthesis of mathematical models of structural systems using experimentally measured component modes that have been enhanced by mass interface loading. With this technique, individual components are tested with arbitrary discrete masses added to interface points. This generates mode shape vectors with increased curvature near the interface to better account for local flexibility effects, and concentrates additional flexible body modes in the measurement frequency bandwidth. The effect of the interface mass is then analytically removed before the component is assembled into the global system. Results of an analytical study, using this technique on a simple beam structure, are given that show significant improvement in predicting system modes compared to using only free-free interface modes. An example is provided which assembles the same structure using an experimentally defined component with a finite element model. Results from this study indicate significant improvement in the assembled system properties. 12 refs., 9 figs., 2 tabs.