Experimental Investigation of Vibrating Laminated Composite Plates by Optical Interferometry Method

Abstract

Most of the work done for the vibration of composite plates published in the literature are analytical and numerical studies with few experimental results available. In this study, an experimental amplitude-uctuation electronic speckle pattern interferometry method for out-of-plane displacement measurement is employed to investigate the vibration behavior of square and rectangular composite plates with different stacking sequences. Both resonant frequencies and corresponding mode shapes can be obtained experimentally using the present method. High-quality interferometric fringes for mode shapes are produced instantly by a video recording system. Four different types of geometric con gurations and stacking sequences of 16-layer laminated composite plates are investigated in this study, namely, a [0] 16 square plate, a [0] 16 rectangular plate, a [0/45/90/¡ ¡ 45] 2s square plate, and a [0/45/90/¡ ¡ 45] 2s rectangular plate. The numerical calculations by the nite element method and Rayleigh-Ritz technique are performed, and the results are compared with the experimental measurements. Good agreement is obtained for both results of resonant frequencies and mode shapes. Nomenclature D i j = laminate bending stiffness w = transverse displacement ¸= wavelength of laser ½ = mass density ! = vibration frequency