The vibration and stability behavior of freely supported FGM conical shells subjected to external pressure

We use the generalized differential quadrature method (GDQ) and shell theories of different order to study free vibrations of laminated cylinders of oval and elliptic cross-sections. In the GDQ method partial derivatives of a function at a point are expressed as weighted sums of values of the function at several neighboring points. Thus, strong forms of equations of motion are analyzed. It is found that the computed frequencies rapidly converge with an increase in the number of grid points along the oval or elliptic circumference defining the cross-section of the mid-surface of the cylinder. For a clamped-free elliptic cylinder the converged frequencies match well with the corresponding experimental ones available in the literature. Furthermore, the lowest ten frequencies computed with either an equivalent single layer theory or a layer wise theory of first order and using shear correction factor are accurate.

Free vibrations of composite oval and elliptic cylinders by the generalized differential quadrature method

Vibrations of rotating cross-ply laminated circular cylindrical shells with stringer and ring stiffeners

An energy method for free vibration analysis of stiffened circular cylindrical shells

In this research, the free vibration analysis of cylindrical shells with circumferential stiffeners, i.e. rings with non-uniform stiffeners eccentricity and unequal stiffeners spacing is investigated using analytical, experimental and finite elements (FE) methods. Ritz method is applied in analytical solution while stiffeners treated as discrete elements. The polynomial functions are used for Ritz functions and natural frequency results for simply supported stiffened cylindrical shell with equal rings spacing and constant eccentricity is compared with other's analytical and experimental results, which showed good agreement. Also, a stiffened shell with unequal rings spacing and non-uniform eccentricity with free–free boundary condition is considered using analytical, experimental and FE methods. In experimental method, modal testing is performed to obtain modal parameters, including natural frequencies, mode shapes and damping in each mode. In FE method, two types of modeling, including shell and beam elements and solid element are used, applying ANSYS software. The analytical and the FE results are compared with the experimental one, showing good agreements. Because of insufficient experimental modal data for non-uniformly stiffeners distribution, the results of modal testing obtained in this study could be as useful reference for validating the accuracy of other analytical and numerical methods for free vibration analysis.

Free vibration of non-uniformly ring stiffened cylindrical shells using analytical, experimental and numerical methods

Free vibration analysis for ring and stringer stiffened cylindrical shell, using Rayleigh-Ritz technique

An analysis of free vibration of orthogonally stiffened cylindrical shells with stiffeners treated as discrete elements.

Thin shell isotropic clamped free elliptical cylindrical shells with various cross sectional eccentricities, measuring frequencies and mode shapes by vibration analysis

John L. Sewall

Papers

An analysis of free vibration of orthogonally stiffened cylindrical shells with stiffeners treated as discrete elements.

Vibration study of clamped-free elliptical cylindrical shells

SPAR analysis of LDEF vibration characteristics

Flutter investigation of a true-speed dynamic model with various tip-tank configurations

An analysis of free vibration of orthogonally stiffened cylindrical shells with stiffeners treated as discrete elements.