Vibration analysis of elastically restrained laminated composite sound radiation plates via a finite element approach

The vibration characteristics (natural frequencies and vibration shapes) of elastically restrained laminated composite plates used for sound radiation are studied via both theoretical and experimental approaches. The laminated composite sound radiation plates restrained by peripheral and/or interior elastic supports are excited using an electro-magnetic exciter for generating sounds. In the theoretical study, a finite element formulation is presented to model the free and forced vibrations of the elastically restrained laminated composite plate. The present finite element method is then used to study the effects of support conditions, plate aspect ratio, and size ratio of plate length to voice coil radius on the vibration characteristics of the elastically restrained laminated composite sound radiation plates. In the experimental study, several centrally restrained laminated composite plates were subjected to sweep sine excitation to determine the frequency response spectra from which the natural frequencies of the plates were identified. The elastically restrained laminated composite plates with salt powder distributed on their top surfaces were excited to generate the vibration shapes of the plates at several selected frequencies. The experimental results are then used to verify the feasibility and accuracy of the proposed finite element model. The close agreement between the experimental and theoretical results has validated the suitability of the proposed finite element model for vibration analysis of sound radiation plates. The theoretical and experimental results presented in this paper can also serve as benchmarks for verifying the correctness of any analytical model established for vibration analysis of laminated composite sound radiation plates. (C) 2013 The Authors. Published by Elsevier Ltd.