Finite element free vibration analysis of rotating laminated composite pretwisted cantilever plates

A finite element method for free vibration characteristics of rotating laminated composite pretwisted cantilever plates is presented. A nine noded three-dimensional degenerated composite shell element is developed and used for the present analysis. A trigonometric increment of pretwist angle along the plate length is considered. The cubic polynomial approximation is assumed for pretwist angle along each elemental length. Plates with exponentially varying thickness and variable chordwise width are studied. Results are obtained to investigate the effects of angle of pretwist, thickness ratio, fibre orientation, aspect ratio, skew angle and precone angle on the natural frequencies of graphite/epoxy plates.