The analysis of vibration characteristics for various shaped composite wings was performed by the finite element method based on shear deformable theory. Three degrees of freedom used in a four node isoparametric element are a vertical displacement and two rotations. The wing is composed of Graphite/Epoxy composite materials. Symmetric stacking sequence has been adapted in this analysis. This paper presents the effects of sweptback angles and fiber orientation on the vibration characteristics. The first mode of all sweptback wing is the first bending mode regardless of the fiber orientation. However, the torsional mode (2nd mode) changes to the 2nd bending mode as the fiber angle increases when the sweep back angle is less than 50 degree. When the sweep back angle is 60 degree, the 2nd mode become 2nd bending mode regardless of the fiber orientations.
In the case of 40 degree sweptback wing, the 2nd and the 3rd natural frequencies becomes very close when the fiber angle is near 8 degree. In the higher modes, we can see the similar mode shape changes due to the fiber orientation.
