The Predicted and Experimental Natural Modes of Free-Free CFRP Plates

Abstract

This paper describes an investigation into the natural modes of free-free laminated composite plates. Theoretical and experimental natural fre quencies and mode shapes are presented for the first six flexural modes of a square aluminium plate and for square CFRP plates of different ply orientations; results are also given for a trapezoidal CFRP plate. The the oretical predictions were made by using an 8-node, 40 degree of freedom shell finite element which allows for transverse shear deformation. The agreement between theoretical and experimental frequencies is good, the worst error being 6.3 per cent. The results indicate that the element pro vides a useful tool in the analysis of laminated composite structures.