Axisymmetric Free Vibrations of Conical Shells

The lowest axisymmetric modes of vibration of truncated conical shells are studied by means of a Rayleigh-Ritz procedure. Transverse shear deformation and rotatory inertia effects are accounted for, and the results are compared with those predicted by the classical thin-shell theory. Additionally, the results are compared when either of these theories is formulated in two ways: First, in the manner of Love’s first approximation in the classical thin-shell theory, and then by including the influence of the change of the element of arc length through the thickness. It was found that the Love and the more complex formulation yielded results which differed negligibly in either theory. The results predicted by the shear deformation-rotatory inertia theory differed significantly from those predicted by the classical thin-shell theory within a range of parameters which characterize short thick cones. These differences resulted principally from the influence of the transverse shear deformation. It was also found that within this short-cone range an increase in the shell thickness parameter was accompanied by an increase in the natural frequency. Moreover, the increase in frequency with increasing thickness parameter became less severe as the length-to-mean radius ratio was increased. For the longer cones, the frequency was virtually independent of the thickness.