Abstract
A coupling system or Vibro-Acoustical system is defined as the coupling between the structural dynamic behavior of a system, structural system, and its interior acoustical characteristics, acoustical system. A coupling system describes a relation between the acoustical responses in the cavity and the structural excitation, and also a relation between the acoustical loading and the structural responses. Examples of real-life coupling systems are aircraft fuselage and car interiors. Reduction of noise and vibration levels for these systems is an important task for human safety and comfort. It is understood that noise in enclosures strongly relates to the vibration of structural systems. However, in many cases vibration levels are reduced, noise in enclosures is not decreased as expected i.e., it is not easy to clearly understand the relationship between structural vibration and enclosure sound. With the purpose to control noise in enclosures, it is necessary to investigate coupling systems to understand their characteristics i.e., to identify modal parameters of these coupling systems. Fatigue and comfort problems, in particular, can be avoided through the knowledge of those modal parameters. Nowadays, in fact, it is always difficult to identify modal parameters of coupling systems. Researchers have tried a lot to solve and to overcome these difficulties to acquire those parameters. However, it is still to be as a challenging job. Many researches have focused on identifying the modal parameters of coupling systems. This research is among of them, it focuses on the experimental analysis of coupling systems. The NLS, Non-linear Least Squares, is presented as a reliable tool for identifying such parameters. In this investigation, vibration and acoustical measurements with respect to acoustical or structural excitation are combined together and then analyzed. The acquired results tell us the reliability of NLS with a coupling system.
Keywords: Vibro-Acoustical System, Coupling System, NVH, Modal Parameter, CAE