• Structural Engineering and Mechanics
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• v.20 no.2
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• pp.241-257
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• 2005

A numerical approach combining the finite element method with two different stability criteria namely the Budiansky and the phase-plane buckling criteria is used to study the dynamic buckling phenomena of plate and shell structures subjected to sudden applied loading. In the finite element analysis an explicit time integration scheme is used and the two criteria are implemented in the Finite Element analysis. The dynamic responses of the plate and shell structures have been investigated for different values of the plate and shell imperfection factors. The results indicate that the dynamic buckling time, which is normally considered in predicting elasto-plastic buckling behavior, should be taken into consideration with the buckling criteria for elastic buckling analysis of plate and shell structures. By selecting proper control variables and incorporating them with two dynamic buckling criteria, the unique dynamic buckling load can be obtained and the problems of ambiguity and contradiction of dynamic buckling load of plate and shell structure can be resolved.

• Steel and Composite Structures
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• v.22 no.6
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• pp.1445-1463
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• 2016

The effects of moisture and temperature on buckling of laminated composite cylindrical shell panels are investigated both numerically and experimentally. A quadratic isoparametric eight-noded shell element is used in the present analysis. First order shear deformation theory is used in the present finite element formulation for buckling analysis of shell panels subjected to hygrothermal loading. A program is developed using MATLAB for parametric study on the buckling of shell panels under hygrothermal field. Benchmark results on the critical loads of hygrothermally treated woven fiber glass/epoxy laminated composite cylindrical shell panels are obtained experimentally by using universal testing machine INSTRON 8862. The effects of curvature, lamination sequences, number of layers and aspect ratios on buckling of laminated composite cylindrical curved panels subjected to hygrothermal loading are considered. The results are presented showing the reduction in buckling load of laminated composite shells with the increase in temperature and moisture concentrations.

• Steel and Composite Structures
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• v.27 no.5
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• pp.555-566
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• 2018

A 1/3 composite cylindrical shell with a central rectangular opening was axially compressed experimentally, and its critical buckling load and displacement, and strains were measured. A finite element model (FEM) of the shell with Hashin failure criteria was established to analyze its buckling and post-buckling behaviors by nonlinear Newton-Raphson method. The geometric imperfection sensitivity and the effect of side supported conditions of the shell were investigated. It was found that the Newton-Raphson method can be used to analyze the buckling and post-buckling behaviors of the shell. The shell is not sensitive to initial geometric imperfection. And the support design of the shell by side stiffeners is a good way to obtain the critical buckling load and simplify the experimental fixture.

• Steel and Composite Structures
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• v.45 no.2
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• pp.175-191
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• 2022

A review of previous studies shows that although there is a considerable difference between buckling loads of structures under follower and non-follower lateral loads, only the buckling load of FGM elliptical cylindrical shell under non-follower lateral load was investigated in the literature. This study is the first to obtain the buckling load of elliptical FGM cylindrical shells under follower lateral load and also make a comparison between buckling loads of elliptical FGM cylindrical shells under follower and non-follower lateral loads. Moreover, this research is the first one to derive the load potential function of elliptical cylindrical shell. In this regard, the FGM cylindrical elliptical shell was modeled using the semi-analytical finite strip method and based on the First Shear Deformation Theory (FSDT). The shell is discretized by strip elements aligned in the longitudinal direction. The Lagrangian and harmonic shape functions were considered in the circumference and longitudinal directions, respectively. The buckling pressure of the shell under follower and non-follower lateral loads was obtained from eigenvalue problem. The results obtained from the model were compared with those presented in the literature to evaluate the validity of the model. A comparison index was defined to compare the buckling loads of the shell under follower and non-follower lateral load. A parametric study was carried out to investigate the effects of material properties and shell geometry characteristics on the comparison index. For the elliptical cylindrical shells with length-to-radius ratio greater than 16 and major-to-minor axis ratio greater than 0.6, the comparison index reaches to more than 20 percent which is significant. Moreover, the maximum difference is about 30 percent in some cases. The results obtained from the parametric study indicate that the buckling load of long elliptical cylindrical shell under non-follower load is not reliable.

• Structural Engineering and Mechanics
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• v.4 no.4
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• pp.451-460
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• 1996

We propose a new shape of cylindrical shell formed by multiples vaults which gives a self-stiffening against buckling. By an experimental and numerical study of cylindrical shells with a repeated defect, on the circumferential direction made only of outside oriented wave-defects, we show that multiple vault cylindrical shells can have a good behaviour in buckling. An optimal behaviour is obtained by optimization of the vaults number, with conduces to a special multiple vault cylindrical shell named "ASTER shell".

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.10a
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• pp.258-265
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• 1998

Application of the flat shell element with drilling D.O.F to linear buckling analysis of thin-walled structures is presented in this paper. The shell element has been developed basically by combining a membrane element with drilling D.O.F. and Mindlin plate bending element. Thus, the shell element possesses six degrees-of-freedom per node which, in addition to improvement of the element behavior, permits an easy connection to other six degrees-of-freedom per node elements(CLS, Choi and Lee, 1995). Accordingly, structures like folded plate and stiffened shell structure, for which it is hard to find the analytical solutions, can be analyzed using these developed flat shell elements. In this paper, linear buckling analysis of thin-walled structures like folded plate structures using the shell elements(CLS) with drilling D.O.F. to be formulated and then fulfilled. Subsequently, buckling modes and the critical loads can be output. Finally. finite element solutions for linear buckling analysis of folded plate structures are compared with available analytic solutions and other researcher's results.

• Steel and Composite Structures
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• v.44 no.5
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• pp.651-676
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• 2022

Most of the experimental, theoretical, and numerical studies on the stability of functionally graded composites are deterministic, while there are full of complex interactions of variables with an inherently probabilistic nature, this paper presents a non-intrusive framework to investigate the stochastic nonlinear buckling behaviors of porous functionally graded cylindrical shells exposed to inevitable source-uncertainties. Euler-Lagrange equations are theoretically derived based on the three variable refined shear deformation theory. Closed-form solutions for the shell buckling loads are achieved by solving the deterministic eigenvalue problems. The analytical results are verified with numerical results obtained from finite element analyses that are conducted in the commercial software ABAQUS. The non-intrusive framework is completed by integrating the Monte Carlo simulation with the verified closed-form solutions. The convergence studies are performed to determine the effective pseudorandom draws of the simulation. The accuracy and efficiency of the framework are verified with statistical results that are obtained from the first and second-order perturbation techniques. Eleven cases of individual and compound uncertainties are investigated. Sensitivity analyses are conducted to figure out the five cases that have profound perturbative effects on the shell buckling loads. Complete probability distributions of the first three critical buckling loads are completely presented for each profound uncertainty case. The effects of the shell thickness, volume fraction index, and stochasticity degree on the shell buckling load under compound uncertainties are studied. There is a high probability that the shell has non-unique buckling modes in stochastic environments, which should be known for reliable analysis and design of engineering structures.

• Bulletin of the Society of Naval Architects of Korea
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• v.24 no.1
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• pp.42-50
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• 1987

The energy expressions are formulated for the axially stiffened shell treating the stiffeners as discrete elements. The principle of minimum potential energy is employed to formulate the buckling equations for a simply supported, axially stiffened shell under uniform axial compression. The displacement functions are expended into double trigonometric series. The mode assuming method employed in this paper makes it possible to reduce the matrix size of the eigenvalue problem considerably. Effects are made to investigate the transition from overall buckling to local buckling and to verify the existence of the minimum stiffness ratio of stiffener as in the case of stiffened plate. The results of the calculation show that the critical stiffener size increase linearly as the length of the shell increases. The results also show that the overall buckling load decreases and the local buckling load has a nearly constant value as the length of the shell increases. The results show very good agreements with other computational available.

• Steel and Composite Structures
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• v.51 no.5
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• pp.543-562
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• 2024

While the external axial compressive load is applied to only the shell edge of stringer-stiffened shell in the most of numerical and analytical previous studies (entitled as conventional approach), a part of external load is applied to the stringers in real conditions. It leads to decrease the accuracy of the axial buckling load calculated by the conventional eigenvalue analysis approach performed in the most of previous studies. In this study, the distribution of stress in the pre-buckling analysis was enhanced by applying the axial external compressive load to both shell and stringers to perform an accurate eigenvalue analysis of the stringer-stiffened composite shell. In this regard, a model was developed in FORTRAN environment to simulate the laminated stringer-stiffened shell under axial compressive load using finite strip method. The axial buckling load of the shell was obtained through eigenvalue analysis. A comparison was made between the results obtained from the model and those available in the previous studies to evaluate the validity of the results obtained from the model. Through a parametric study, the effects of different parameters such as stringer properties and composite layup on the buckling load of the shell under different loading patterns were investigated. The results indicated that in some cases, the axial buckling load obtained for the conventional approach used in the most of previous studies is significantly overestimated or underestimated due to neglecting the stringer in distribution of external load applied to the stringer-stiffened shell. According to the results obtained from the parametric study, some graphs were derived to show the accuracy of the axial buckling load obtained from the conventional approach utilized in the literature.

• Nuclear Engineering and Technology
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• v.35 no.6
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• pp.537-546
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• 2003

The purpose of this paper is to investigate the buckling characteristics of a conceptually designed KALIMER-150(Korea Advanced LIquid MEtal Reactor, 150MWe) reactor vessel and verify the buckling behavior using the reduced scale cylindrical shell structures. To do this, nonlinear buckling analyses using finite element method and evaluation formulae are carried out. From the results, the KALIMER-150 reactor vessel exhibits a dominant bending buckling mode and is significantly affected by the plastic behavior. The interaction effects with the vertical seismic load cause the lateral buckling load to be slightly decrease. From the results of the buckling experiments using reduced scaled cylindrical shell structures, it is verified that the buckling modes such as pure bending, pure shear, and mixed(bending plus shear) mode clearly appear under a lateral load corresponding to the slenderness ratio of cylinder.