Abstract:

The dynamical behavior of a complex structure at midfrequencies poses special analytical modeling challenges. Traditionally, finite-element analysis (FEA) has been viewed as an analysis method for low-frequency vibrations, while statistical energy analysis (SEA) has been used to analyze high-frequency vibrations. Ongoing work funded by the RESOUND Consortium is directed at bridging the gap between these two methods to produce an analysis technique which is applicable across the whole frequency range, including the problematic ``midfrequency'' region. A novel wave-number partitioning scheme has been developed under which the system dynamic response is represented as a combination of finite-element ``global modes'' and SEA subsystem ``local modes.'' It has been found that the interaction between these two sets of modes encompasses many of the features of ``fuzzy structure theory,'' an area of great current interest in structural dynamics. In many design situations a (relatively) course mesh finite-element model of a vehicle is developed to study static and low-frequency dynamical behavior. Such a model can be incorporated into the proposed method without the need for labor intensive remodeling. This paper will describe initial applications of the method that was introduced by the authors in a previous [J. Acoust. Soc. Am. 100, 2754(A) (1996)]. In particular, it will present the results of some experimental validation of the method applied to midfrequency vibration response of a truss-frame structure.