Finite element vibration analysis of composite skew laminates containing delaminations around quadrilateral cutouts

The free vibration analysis of laminated composite skew plates with delamination around a centrally located quadrilateral cutout is carried out based on the high-order shear deformation theory (HSDT) in this study. In the finite element formulation for the delamination around cutout, the seven degrees-of-freedom per each node are used with transformations in order to fit the displacement continuity conditions at the delamination region. The numerical results obtained for the rectangular plates are in good agreement with those of other preceding investigations. The new results for skew plates in this study mainly show the effect of the interactions between the skew angle and other various parameters, for example, cutout size, delamination area, and length-to-thickness ratio. Key observation points are discussed and a brief design guideline is given.