Recent Developments in Multiple Input Modal Analysis

Abstract

Over the last two decades in experimental modal analysis many different approaches have been developed for application to a great variety of structural engineering problems. The effectiveness of modal testing depends directly on the capability to construct optimal excitation force vectors in order to identify a complete set of normal modes in a frequency band of interest and to extract the corresponding modal parameters. These tasks can be considerably facilitated by means of so-called mode indicator functions (MIF) the most current of which will be thoroughly investigated in order to reveal their features and capabilities. Furthermore, emphasis will be placed on the problem of finding appropriate force vectors to excite either real or complex normal modes. A new concept to determine optimal force vectors for the excitation of complex normal modes will be presented. In the context with the definition of complex normal modes the problem of transforming complex normal modes into real normal modes will be treated as well.