Structural Dynamics Modification and Modal Modeling

Abstract

The structural dynamics modification (SDM) method, also called eigenvalue modification, was first commercialized in the earlier 1980s by a software company founded by the authors. It has proved to be a useful engineering tool for providing a quick look at the influence of physical modifications to a mechanical structure on its modes of vibration.

SDM can be used with experimental mode shapes as well as analytical mode shapes. It provides meaningful results even when used with a few mode shapes and combined experimental and analytical mode shape data. This chapter also provides background information on the many details to be considered when acquiring experimental mode shapes. Finally, the example provided shows that SDM gives very accurate results when both translational and rotational joint stiffnesses are used to model the attachment of a rib stiffener to a plate.