Recent research advances in the dynamic behavior of shells: 1989-2000, Part 1: Laminated composite shells

Postbuckling analysis of stiffened laminated cylindrical shells under combined external liquid pressure and axial compression

A C 0 finite element formulation using a higher-order shear deformation theory (HSDT) is developed and used to analyse the buckling behaviour of laminated hypar and conoids. Higher order terms in the Taylor's series expansion are used to represent the higher-order transverse cross-sectional deformation modes. The formulation includes Sanders' approximation for doubly curved shells considering the effect of transverse shear. A realistic parabolic distribution of transverse shear strains through the shell thickness is assumed and the use of shear correction factor is avoided. The accuracy of the formulation is validated by carrying out convergence study and comparing the results with those available in the literature.

Buckling of laminated composite hypars and conoids using a higher-order theory

In this study, the free vibration behavior of axially compressed cross-ply laminated composite cylinders is investigated using a semi-analytical shell finite element based on a consistent first order shear deformable shell theory, which includes the influences of rotatory inertia and thickness coordinate/radius ratio. First, a verification study is conducted to validate the axisymmetric shell finite element used in this study and, for the non-compressed cases, the free vibration frequencies obtained using the finite element developed are found out to be in excellent agreement with the published results found in the literature. The same element is also validated for first-ply failure analysis and good agreement is observed with the first-ply failure loads obtained using a shear deformable and curved shell element. Then, numerical results for free vibration analyses are presented for axially compressed composite cylinders having different boundary conditions and for which the level of axial compression is kept below the corresponding linear buckling and first ply failure loads. It is observed that, the fundamental free vibration frequencies decrease sharply for axial load levels higher than about 60~80% of the buckling loads of the cylindrical structures considered. It is also determined that the first-ply failure load is lower than the buckling load for some of the thicker cylinders .

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The Influence of Axial Compression on the Free Vibration Frequencies of Cross-ply Laminated and Moderately Thick Cylinders

A semi-analytical isoparametric finite element with three nodes per element and five degrees of freedom per node has been used for the solution. Moderately thick shell theory has been used for the analysis. Second order strains with the in plane and transverse non-linear terms are used for the derivation of geometric matrix. Full Fourier expansion is used in the circumferential direction to overcome the coupling that arises due to material anisotropy and torque prestress. Comparison of the results obtained due to finite element is made with simplified solutions using two thin shell theories with and without shear deformation. The effects of combined load (axial compression and external pressure) on pre-buckling characteristics of composite circular cylindrical and conical shells of various geometric properties have been presented.

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Buckling analysis of shells subjected to combinted loads

An analytical solution is presented for the stability and free vibration of the cross-ply laminated thin circular cylindrical shells which are simply supported at both ends and subject to axial and lateral pressure. Based on the principles of virtual work and a nine-term higher order transverse shear and transverse normal deformable displacement field, a set of governing equations for thermal buckling of thin circular cylindrical shells together with the associated boundary conditions are derived. Navier double series method is then applied to find the closed-form solutions. Effects of important parameters such as degree of orthotropy, ratio of length to radius, ratio of radius to thickness, etc., are studied.

Buckling and free vibration of cross-ply laminated circular cylindrical shells subjected to axial thrust and lateral pressure loading according to a higher order displacement field

Jeng-Shian Chang

Papers

Buckling and free vibration of cross-ply laminated circular cylindrical shells subjected to axial thrust and lateral pressure loading according to a higher order displacement field