Natural Frequencies and Mode Shapes of Composite Conoids with Complicated Boundary Conditions

Abstract

A finite element code is developed using an eight-noded curved quadratic isoparametric element and the formulation is validated through solution of a benchmark problem which was earlier solved by other researchers. Numerical problems are solved for ten different practical boundary conditions and for different symmetric and antisymmetric laminations of conoidal shells on square planform to study the performances of different shell options in terms of fundamental frequencies. Effects of number of boundary constraints and arrangement of boundary conditions along the four edges on fundamental frequencies are studied meticulously and also performance of symmetric and antisymmetric laminations are compared in detail. A comparative performance study of cross ply and angle ply laminations is also made. Specific conclusions are drawn at the end, to summarize the outcome of the present investigation that are expected to serve as important guidelines to engineers engaged in analysis, design, and construction of composite shells.