Free vibration analysis of symmetrically laminated composite circular plates with curvilinear fibers

Abstract

The free vibration analysis of symmetrically laminated composite circular plates with curvilinear fibers is performed using the first-order shear deformation theory along with a curved hierarchical square finite element. The blending function method is used to describe accurately the geometry of the circular plate. The hierarchical shape functions are constructed from Legendre orthogonal polynomials. The element stiffness and mass matrices are integrated numerically by means of the Gauss-Legendre quadrature. The equations of motion are derived using Lagrange’s method. Results for the fundamental frequency are obtained for clamped and soft simply supported laminated composite circular plates with E-glass, graphite, and boron curvilinear fibers in epoxy matrices. The element is validated by means of the convergence test and comparison with published data for isotropic and laminated composite circular plates with rectilinear fibers. Contour plots of frequency as a function of fiber orientation angles for laminated composite circular plates with curvilinear fibers are presented. The fiber material and boundary conditions are shown to influence the distribution of frequency throughout the design space. Frequency curves as a function of fiber orientation angles for the first five modes of laminated composite circular plates with curvilinear fibers are also presented. They reveal that none of the first five modes of clamped and soft simply supported laminates is affected by crossing but modes 3 and 4 of clamped graphite/epoxy and boron/epoxy laminates are affected by veering.

Keywords

• curved hierarchical square finite element
• curvilinear fiber
• first-order shear deformation theory
• free vibration
• laminated composite circular plate