Analysis Of Circular Cylindrical Shells Research Articles

Field-Consistent Element Applied to Flutter Analysis of Circular Cylindrical Shells

Supersonic flutter analysis of laminated composite circular cylindrical shells is investigated by using an axisymmetric shell finite element based on the field-consistency approach. The formulation includes transverse shear deformation and in-plane and rotary inertia effects. The aerodynamic force is evaluated by considering the first order high Mach number approximation to linear potential flow theory. The solution for the complex eigenvalue problem is obtained by the QR algorithm. Numerical results are presented for isotropic, orthotropic and laminated anisotropic circular cylindrical shells. A detailed parametric study is carried out to observe the effects of aspect ratio, thickness, internal pressure, axial compression, number of layers and lamination scheme on the flutter boundary.

Dynamic Analysis of Circular Cylindrical Shells with Material Damping

The dynamic response of shells plays an important role in structural dynamics. In the present paper, one of the widely used shells of revolution, a circular cylindrical shell, is analyzed for its dynamic response due to different types of transient loads. A first order shell theory with shear deformation and rotatory inertia (improved) is used for the solution in conjunction with a higher order subparametric axisymmetric finite element with 25 degrees of freedom per element. The effect of material damping on dynamic stress response is also studied. Isotropic and laminated shells of different boundary conditions are considered for the solution.

Bifurcation creep buckling analysis of circular cylindrical shell under axial compression

In some experiments conducted by other authors, axially compressive cylindrical shells with a large ratio of radius to thickness were observed to buckle with circumferential waves. In this paper, the finite element method is used to study this buckling phenomenon. The bifurcation mode and the axisymmetric mode were considered in the analysis as the mode of creep buckling. The number of circumferential waves obtained from the present analysis agrees well with experimental results. This implies that the circumferential waves observed in the creep buckling experiments are due to bifurcation.

Limit Loads of Cylindrical Shells under Hydrostatic Pressure

The limit analysis of circular cylindrical shells under hydrostatic pressure is formulated as a mathematical programming problem using the static theorem of plasticity. The governing differential equilibrium equations and force boundary conditions are linearized through a finite difference scheme. This discretization is combined with a piecewise linearization of the nonlinear yield curve to convert the formulation into a conventional linear programming exercise. This approach is shown to be superior to the more commonly used analytical techniques. In particular, it is general, systematic, and does not require prior knowledge of the stress field or collapse mechanism. In spite of the fact that a lower-bound solution is not guaranteed due to possible yield violation at unchecked points in the structure, very accurate solutions can be obtained by suitably refining the finite difference mesh and, if necessary, the yield polygon. Examples of reported cases are solved to illustrate ease of application of the method, its flexibility, and accuracy.

Vibration analysis of circular cylindrical shells connected to bellows.

For the purpose of decreasing the lower critical speed of circular cylindrical shells which are used in centrifugal separators for uranium enrichment, and rotating at higher speeds, we consider circular cylindrical shells connected to bellows. Vibration analysis of circular cylindrical shells connected to bellows is carried out by the substructure synthesis method for various numbers and dispositions of bellows, and the optimum ones are examined. Moreover, the transfer matrix method, by which the critical speeds are simply obtained, is described, and the results are examined by the substructure synthesis method.

STRESS ANALYSIS OF CIRCULAR CYLINDRICAL SHELLS WITH FLANGE AND RIB ASSEMBLY

Static analysis of circular cylindrical shell with ribs and flange assembly subjected to axisymmetric and asymmetric loading is carried out. Finite element method using cyclic symmetric is used. The Potter’s method is modified to solve the simultaneous equation of cyclic symmetry analysis. An experimental model was tested for static axisymmetric and asymmetric loading. The results are compared with the theoretical ones.

Postbuckling analysis of circular cylindrical shells under external pressure

The postbuckling behavior of circular cylindrical shells of finite length under uniform external pressure is analysed using the spline finite strip method. A Total Lagrangian formulation on the displacement dependent pressure load in the orthogonal curvilinear reference frame is derived. An improvement for the arc-length iteration method is presented. The postbuckling equilibrium path and the contour map of equal radial deflection computed are in good agreement with the experimental and analytical results reported in Esslinger, M. and Geier, B., Postbuckling Behaviour of Structures, Springer-Verlag, Wien, New York, 1975.

Vibration analysis of cylindrical shells connected with bellows.

For the purpose of decreasing the lower critical speed of circular cylindrical shells, which are used in centrifugal separators to enrich uranium, and rotating at higher speeds, it is considered that circular cylindrical shells are connected with bellows. Vibration analysis of circular cylindrical shells connected with bellows is carried out by the substructure synthesis method for various numbers and dispositions of bellows, and the optimum ones are examined. Moreover, the transfer matrix method, by which the critical speeds are simply obtained, is described and the results are examined by the substructure synthesis method.

Creep buckling analysis of circular cylindrical shell under both axial compression and internal or external pressure

This paper deals with the creep buckling of a circular cylindrical shell subjected to both axial compression and internal or external pressure. The finite element method is applied to a creep deformation analysis to obtain the critical time when the creep buckling occurs. Two types of creep buckling are considered in the present analysis. One is the axisymmetric mode of creep buckling due to the quasi-static instability. The other is the asymmetric mode of creep buckling due to the bifurcation. The effects of internal or external pressure on the creep buckling are clarified by the present analysis.

Free vibration analysis of circular cylindrical shells

Determination of the vibrational characteristics of circular cylindrical shells often requires significant computational effort. This paper presents the results of a comprehensive, computer based, numerical investigation of the free vibration of circular cylindrical shells. An analytical procedure which accurately predicts the natural frequencies and radial mode shapes (corresponding to axial wave number and circumferential wave number both equal to one) for a wide range of circular cylindrical shells is developed. The procedure is applicable to shells either with or without a top closure. Several numerical examples are presented which illustrate application of the procedure and verify its accuracy.

On A Formulation of the Elastic Stability Equations of Circular Cylindrical Shells Under Variable Internal Pressure

The mathematical model of the stability analysis of circular cylindrical shells under arbitrary internal pressure is presented. The paper consists of a direct analysis of the equilibrium modes in the neighbourhood of the unperturbed principal equilibrium path. The final stability condition results in a completely symmetric differential operator which is then compared with current theories found in the literature.

Creep buckling analysis of circular cylindrical shell under axial compression. (Bifurcation buckling analysis by the finite element method)

The finite element method is applied to creep buckling of a circular cylindrical shell under axial compression. In the finite element formulation, nonlinear strain-displacement relation is employed and creep strain is treated as an initial strain within a small time increment. Not only the axisymmetric mode but also the bifurcation mode of creep buckling are considered in the analysis. The critical time for creep buckling is defined as either the time when a slope of a displacement vs. time curve becomes infinite or the time when bifurcation buckling occurs. The creep buckling analyses are carried out for an infinitely long, axially compressed circular cylindrical shell. The numerical results are compared with available analytical ones and experimental data.

Limit Analysis of Circular Cylindrical Shells under Hydrostatic Pressure*

ABSTRACT The problem of limit analysis of circular cylindrical shells under hydrostatic pressure is dealt with. On the basis of Hodge plastic yield condition, solutions are achieved by solving systems of simultaneous algebraic nonlinear equations. Several cases of different boundary conditions are considered.

A higher order theory for free vibration analysis of circular cylindrical shells

The free, undamped vibration of an isotropic circular cylindrical shell is analysed with higher order displacement model, giving rise to a more realistic parabolic variation of transverse shear strains. The method accounts for in-plane inertia, rotary inertia, and shear deformation effects on the dynamic response of cylindrical shells. The frequencies obtained from the present analysis, shear deformation theory, and Flügge theory are compared with the exact elasticity results. It is found that the frequencies predicted by the present analysis are closer to exact values than those predicted by the shear deformation theory, especially for cases with shorter wavelengths.

Free vibration analysis of circular cylindrical shells

A general analytical method is presented for evaluating the free vibration characteristics of a circular cylindrical shell with classical boundary conditions of any type. The solution is obtained through a direct solution procedure in which Sanders' shell equations are used with the axial modal displacements represented as simple Fourier series expressions. Stokes' transformation is exploited to obtain correct series expressions for the derivatives of the Fourier series. An explicit expression of the exact frequency equation can be obtained for any kind of boundary conditions. The accuracy of the method is checked against available data. The method is used to find the modal characteristics of the thermal liner model of the U.S. Fast Test Reactor (FTP). The numerical results obtained are compared with finite element method solutions.

Static analysis of diaphragm‐supported cylindrical shells using a curved finite strip

AbstractTwo versions are presented of a tranversely‐curved finite strip for the static analysis of circular cylindrical shells. The strip is a refined displacement model with sixteen transverse degrees‐of‐freedom arranged either at two or at four nodal lines. The analysis is specialized for cylinders with diaphragm supports at the ends—via the employment of simple trigonometric series in the longitudinal direction—but extension to other end conditions is straightforward in principle. Detailed results of applications of the curved strip are presented.

Transient creep of circular cylindrical shells

Transient creep analysis of circular cylindrical shells on the basis of the strain-hardening and time-hardening theories is presented. Total strain is assumed to consist of elastic and creep components. Equations of equilibrium are replaced by the corresponding difference equations with regard to the rate of displacement, and the solutions of the resulting simultaneous linear equations are integrated numerically with respect to time. Numerical results for stress, membrane force, bending moment and displacement are obtained for simply supported circular cylindrical shells subjected to constant or variable internal pressure. The difference between both kinds of hardening theory as applied to the present problem is discussed.

Creep analysis of circular cylindrical shells

Abstract : Governing equations for nonlinear creep analysis of thin circular cylindrical shells are derived based upon a power law for creep. These equations are solved for a clamped shell subjected to uniform internal pressure. The method of solution is one of iteration where the starting solution is that for the linear case. Stress resultants and deflections are presented for various values of the parameters involved. (Author)

On an approximate method of analysis of circular cylindrical shells

Functionally graded composite materials (FGCMs) are inhomogeneous materials, consisting of two (or more) different materials, engineered to have a continuously varying spatial composition profile . This paper describes the overview of FGCM basic concepts, classification, properties and preparation methods. It focuses on an overview of research and Application of FGCM in broad present situation. Based upon analysis of the present application situations and prospect of this kind of materials some existing problems are discussed As a part of present research work, a simple case study is discussed based on CNT reinforced Al Functionally graded composite by Powder metallurgy technique. An insight in to the current status of the research of FGCM is presented and an anticipation of its future development is also presented.