OPTIMAL DESIGN BY USING VARIOUS SOLUTIONS FOR VIBRATION OF LAMINATED SHALLOW SHELLS ON SHEAR DIAPHRAGMS
✍ Scribed by Y. Narita; T. Nitta
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 246 KB
- Volume
- 214
- Category
- Article
- ISSN
- 0022-460X
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✦ Synopsis
Free vibration and corresponding optimal design problems are solved for laminated composite shallow shells of rectangular planform. The shells have symmetric laminated construction and are supported by shear diaphragms along the edges. The first-order transverse shear deformation is assumed in the Donnell type shell theory to account for the thickness shear effect, and an analytical solution is presented which is exact for cross-ply laminates and is approximate for angle-ply laminates. A simplified formula is also derived by neglecting inplane inertia terms. Analytical solutions with/without the inplane inertia terms from the classical thin shell theory are also shown. In numerical examples, natural frequencies are presented for various types of shell curvature, e.g., circular cylindrical, spherical and hyperbolic paraboloidal shells. Fibre orientation angles, which cause the maximized fundamental frequencies of the alternating angle-ply shells, are determined, and effects of using the four different vibration solutions are discussed on the optimal frequencies and fibre orientation angles. Questions of how the different solutions quantitatively affect the optimal design results and which solution is recommended in the present type of optimization problems are clarified in the conclusions.