• Journal of KSNVE
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• v.9 no.2
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• pp.273-284
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• 1999

The cylindrical shells are used as primary components of complex structures such as airplane fuselages and nuclear pressure vessels. Recently the free vibration analysis of these structures are investigated by many researchers. The engineering informations on experimental validation of the free vibration behavior on the simply supported cylindrical shells are very few. The experimental methods for realizing the physical boundary condition of simply supported edges are examined. Natural frequencies and mode shapes of the isotropic and plain weave composite simply supported shells are obtained by modal tests. A theoretical and finite element analysis are also performed in order to validate the experimental results. The experimental results indicate that the simply supported boundary conditions with bolts along the circumferential direction of shell in both ends are well achieved. Those are shown to agree with the analytical results and with the finite element analysis results. These methods can be used to realize other experimental simple support boundary conditions.

• Steel and Composite Structures
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• v.21 no.2
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• pp.373-394
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• 2016

The postbuckling behavior of laminated composite plates and shells, subjected to various shear loadings, is presented, using a modified 8-ANS method. The finite element, based on a modified first-order shear deformation theory, is further improved by the combined use of assumed natural strain method. We analyze the influence of the shell element with the various location and number of enhanced membrane and shear interpolation. Using the assumed natural strain method with proper interpolation functions, the present shell element generates neither membrane nor shear locking behavior even when full integration is used in the formulation. The effects of various types of lay-ups, materials and number of layers on initial buckling and postbuckling response of the laminated composite plates and shells for various shear loading have been discussed. In addition, the effect of direction of shear load on the postbuckling behavior is studied. Numerical results and comparisons of the present results with those found in the literature for typical benchmark problems involving symmetric cross-ply laminated composites are found to be excellent and show the validity of the developed finite element model. The study is relevant to the simulation of barrels, pipes, wing surfaces, aircrafts, rockets and missile structures subjected to intense complex loading.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.9
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• pp.797-805
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• 2013

In this paper vibration and stability analysis of laminated composite shells based on the first order shear deformation theory(FSDT) for two different boundary conditions(clamped-clamped, simply supported) are performed. Structural model of cross-ply symmetric laminated composite cylindrical shells subjected to a combination of magnetic and thermal fields is developed via Hamilton's variational principle. These coupled equations of motion are based on the electromagnetic equations(Faraday, Ampere, Ohm, and Lorenz equations)and thermal equations which are involved in constitutive equations. Extended Galerkin method is adopted to obtain the discretized equations of motion. Variations of dynamic characteristics of composite shells with applied magnetic field, temperature gradient, laminate thickness-ratio and radius ratio for two boundary conditions are investigated and pertinent conclusions are derived.

• Journal of Korean Society of Steel Construction
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• v.11 no.1 s.38
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• pp.55-67
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• 1999

The ratios of elastic to shear modulus of the structures as laminated composite plates and shells, are very large. They are much susceptible to effect of shear deformation. In order to obtain the accurate solutions of laminated composite plate and shells, the effects of shear strain should be considered for the analysis and design of them. Especially, the more exact solution can be obtained in applying to higher-order shear deformation theory. Therefore, in this paper, the third-order shear deformation theory is used to present the distributions of bending, the characteristics of natural frequencies and the buckling load according to the effects of ply orientation, number of layers for the laminated composite plates and shells with simply supported boundary conditions.

• Steel and Composite Structures
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• v.15 no.4
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• pp.379-397
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• 2013

Conoidal shells are doubly curved stiff surfaces which are easy to cast and fabricate due to their singly ruled property. Application of laminated composites in fabrication of conoidal shells reduces gravity forces and mass induced forces compared to the isotropic constructions due to the high strength to weight ratio of the material. These light weight shells are preferred in the industry to cover large column free open spaces. To ensure design reliability under service conditions, detailed knowledge about different behavioral aspects of conoidal shell is necessary. Hence, in this paper, static bending, free and forced vibration responses of composite conoidal shells are studied. Lagrange's equation of motion is used in conjunction with Hamilton's principle to derive governing equations of the shell. A finite element code using eight noded curved quadratic isoparametric elements is developed to get the solutions. Uniformly distributed load for static bending analysis and three different load time histories for solution of forced vibration problems are considered. Eight different stacking sequences of graphite-epoxy composite and two different boundary conditions are taken up in the present study. The study shows that relative performances of different shell combinations in terms of static behaviour cannot provide an idea about how they will relatively behave under dynamic loads and also the fact that the points of occurrence of maximum static and dynamic displacement may not be same on a shell surface.

• Journal of Korean Society of Steel Construction
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• v.12 no.4 s.47
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• pp.417-428
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• 2000

In recent years, composite materials have been used in civil engineering as well as architecture, automobile, aerospace, shipping industries. Composite materials are composed of two or more different materials to produce desirable properties for structural strength. The shell structures have the advantage of more efficient load resistance due to its curved shape as compared to the plate structures. And the shell structures with composite materials have many advantages in strength, corrosion resistance, and weight reduction. The objective of this study is to analyze circular conical shells with shear deformation effects and to prove the advantage of composite materials. To solve differential equations of conical shells, this paper used finite difference method.

• Journal of the Korean Society for Advanced Composite Structures
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• v.1 no.3
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• pp.17-23
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• 2010

This paper is presented for the analysis results of the bending problems of the anisotropic cylindrical shells. In the numerical analysis of various mechanical problems involving complex partial differential equations, Finite element method is used to analyze the governing equations of anisotropic cylindrical shells. Both thin shell theory and thick shell theory are used as the basic governing equations of bending problems in the anisotropic cylindrical shells. The analysis results are compared between the anisotropic thick cylindrical shells and the anisotropic thin cylindrical shells. The results of this study will be contribute to analyze the bending behavior of anisotropic cylindrical shells.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.9-12
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• 2000

This paper deals with the torsional buckling behavior of plain weave GFRP composite cylindrical shells having comparatively small length-to-diameter ratio. Boundary conditions corresponding to clamped ends and simply supported ends are considered. Torsional buckling loads and circumferential mode numbers according to the variation of shell length-to-radius ratio are conformed. To verify the availability of the theoretical results, comparison with the theoretical and experimental results are made.

• Steel and Composite Structures
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• v.32 no.5
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• pp.687-699
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• 2019

In this paper, free and force vibration behaviors of graphene-reinforced composite functionally graded (GRC-FG) cylindrical shells in thermal environments are investigated based on Reddy's third-order shear deformation theory (HSDT). The GRC-FG cylindrical shells are composed of piece-wise pattern graphene-reinforced layers which have different volume fraction. Based on the extended Halpin-Tsai micromechanical model, the effective material properties of the resulting nanocomposites are evaluated. Using the Hamilton's principle and the assumed mode method, the motion equation of the GRC-FG cylindrical shells is formulated. Using the time- and frequency-domain methods, free and force vibration properties of the GRC-FG cylindrical shell are analyzed. Numerical cases are provided to study the effects of distribution of graphene, shell radius-to-thickness ratio and temperature changes on the free and force vibration responses of GRC-FG cylindrical shells.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.5
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• pp.150-156
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• 2000

The objective of this study is to investigate effects of prebuckling on the buckling of laminated composite cylindrical shells. Axial compression and lateral pressure are considered for laminated composite cylindrical shells with the ratios of length to radius. The shell walls are made of a laminate with several symmetric ply orientations. The study was made using finite difference energy method, utilizing the nonlinear bifurcation branch with nonlinear prebuckling displacements. The results are compared to the buckling loads determined when membrane prebuckling displacements are considered. Review the influence of nonlinear prebuckling for the buckling loads, the difference between the actual and classical buckling loads are increased as the increments with the ratios of length to radius, for which is applied the axial compression, but almost same for the lateral pressure.