• Steel and Composite Structures
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• v.10 no.4
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• pp.361-371
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• 2010

Enhancement in the seismic buckling capacity of steel tanks caused by the addition of fiber reinforced polymers (FRP) retrofit layers attached to the outer walls of the steel tank is investigated. Three-dimensional non-linear finite element modeling is utilized to perform such analysis considering non linear material properties and non-linear large deformation large strain analysis. FRP composites which possess high stiffness and high failure strength are used to reduce the steel hoop stress and consequently improve the tank capacity. A number of tanks with varying dimensions and shell thicknesses are examined using FRP composites added in symmetric layers attached to the outer surface of the steel shell. The FRP shows its effectiveness in carrying part of the hoop stresses along with the steel before steel yielding. Following steel yielding, the FRP restrains the outward bulging of the tank and continues to resist higher hoop stresses. The percentage improvement in the ultimate base moment capacity of the tank due to the addition of more FRP layers is shown to be as high as 60% for some tanks. The percentage of increase in the tank moment capacity is shown to be dependent on the ratio of the shell thickness to the tank radius (t/R). Finally a new methodology has been explained to calculate the location of Elephant foot buckling and consequently the best location of FRP application.

• Steel and Composite Structures
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• v.29 no.1
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• pp.39-51
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• 2018

Position of a circular or elliptical cutout within an orthotropic plate has great influence on its buckling behavior. This paper aims at finding the optimal position (both location and orientation) of a single circular/elliptical cutout, within an orthotropic rectangular plate, that maximizes the critical buckling load. We consider linear buckling of simply supported orthotropic plates under uniaxial edge loads. To obtain the optimal positions of the cutouts, we have employed a MATLAB optimization routine coupled with buckling computation in ANSYS. Our results show that the position of the cutout that maximizes the buckling load has great dependence on the material properties, laminate configurations, and the geometrical parameters of the plate. These optimal results, for a number of plate geometries and cutout sizes, are reported in this paper. These results will be useful in the design of perforated orthotropic plates against buckling failure.

• Computational Structural Engineering : An International Journal
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• v.3 no.1
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• pp.19-29
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• 2003

In the present study, finite element linear buckling analysis is performed for grid-stiffened composite plates. A hybrid element with drilling degrees of freedom is employed to reduce the effect of the sensitivity of mesh distortion and to match the degrees of freedom between skins and stiffeners. The preliminary static stress distribution is analyzed for the determination of accurate load distribution. Parametric study of grid structures is performed and three types of buckling modes are observed. The maximum limit of buckling load was found at the local skin-buckling mode. In order to maximize buckling loads, stiffened panels need to be designed to be buckled in skin-buckling mode.

• Steel and Composite Structures
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• v.31 no.3
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• pp.243-259
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• 2019

This study deals with the nonlinear static analysis of functionally graded carbon nanotubes reinforced composite (FG-CNTRC) truncated conical shells subjected to axial load based on the classical shell theory. Detailed studies for both nonlinear buckling and post-buckling behavior of truncated conical shells. The truncated conical shells are reinforced by single-walled carbon nanotubes which alter according to linear functions of the shell thickness. The nonlinear equations are solved by both the Airy stress function and Galerkin method based on the classical shell theory. In numerical results, the influences of various types of distribution and volume fractions of carbon nanotubes, geometrical parameters, elastic foundations on the nonlinear buckling and post-buckling behavior of FG-CNTRC truncated conical shells are presented. The proposed results are validated by comparing with other authors.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.9
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• pp.119-130
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• 1999

This paper deals buckling behavior of laminated composite cylindrical shells subjected to combination of axial compression and torison. Linear and nonlinear finite element analysis are carried out . the influence of load type, load ratio, fiber orientation angle, stacking sequence, and intial imperfect on buckling behavior is discussed.

• Proceedings of the KSR Conference
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• 2002.05a
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• pp.207-212
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• 2002

The actual buckling of the railroad track structure is suspected to be a complex interaction between the vertical, lateral and torsional modes. To make the analysis tractable, however, most studies restrict themselves to either the vertical or the horizontal plane. Based on a comprehensive and realistic three-dimensional track model developed in the previous study, three dimensional buckling analysis of CWR track subjected to temperature load was performed. Using the study on buckling temperature and mode, sensitivity of track components such as tie spacing, ballast resistance, stiffness of pad-fastening system and rail size were investigated.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.3
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• pp.10-21
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• 2022

The propellant tank, which is a space launch vehicle structure, must have structural integrity as various static and dynamic loads are applied during ground transportation, launch standby, take-off and flight processes. Because of these characteristics, the propellant tank cylinder, the structural object of this study, has a thin thickness, so buckling due to compressive load is considered important in the cylinder design. However, the existing buckling design standards such as NASA and Europe are fairly conservative and do not reflect the latest design and manufacturing technologies. In this study, nonlinear buckling analysis is performed using various analysis models that reflect initial defects, and a method for establishing new buckling design standards for cylinder structures is presented. In conclusion, it was confirmed that an effective lightweight design of the cylinder structure for common bulkhead propulsion tank could be realized.

• Structural Engineering and Mechanics
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• v.62 no.6
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• pp.675-693
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• 2017

In this paper, based on the first-order shear deformation plate theory, buckling analysis of piezoelectric coupled transversely isotropic rectangular plates is investigated. By assuming the transverse distribution of electric potential to be a combination of a parabolic and a linear function of thickness coordinate, the equilibrium equations for buckling analysis of plate with surface bonded piezoelectric layers are established. The Maxwell's equation and all boundary conditions including the conditions on the top and bottom surfaces of the plate for closed and open circuited are satisfied. The analytical solution is obtained for Levy type of boundary conditions. The accurate buckling load of laminated plate is presented for both open and closed circuit conditions. From the numerical results it is found that, the critical buckling load for open circuit is more than that of closed circuit in all boundary and loading conditions. Furthermore, the critical buckling loads and the buckling mode number increase by increasing the thickness of piezoelectric layers for both open and closed circuit conditions.

• Structural Engineering and Mechanics
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• v.60 no.2
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• pp.271-299
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• 2016

In this article, based on the higher-order shear deformation plate theory, buckling analysis of a rectangular plate made of functionally graded piezoelectric materials and its effective parameters are investigated. Assuming the transverse distribution of electric potential to be a combination of a parabolic and a linear function of thickness coordinate, the equilibrium equations for the buckling analysis of an FGP rectangular plate are established. In addition to the Maxwell equation, all boundary conditions including the conditions on the top and bottom surfaces of the plate for closed and open circuited are satisfied. Considering double sine solution (Navier solution) for displacement field and electric potential, an analytical solution is obtained for full simply supported boundary conditions. The accurate buckling load of FGP plate is presented for both open and closed circuit conditions. It is found that the critical buckling load for open circuit is more than that of closed circuit in all loading conditions. Furthermore, it is observed that the influence of dielectric constants on the critical buckling load is more than those of others.

• Steel and Composite Structures
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• v.23 no.6
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• pp.647-656
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• 2017

This paper presents an experimental study on the behaviour of steel beams with different types of web openings. Steel beams with web openings became progressively more accepted as a well-organized structural form in steel construction since their existence. Their complicated design and profiling method provides better flexibility in beam proportioning for strength, depth, size and location of holes. The objective of this study is to carry out the experiments on steel beams with different types of web openings and performed non-linear finite element (FE) analysis of the beams that were considered in the experimental study in order to determine their ultimate load capacity and failure modes for comparison. Ten full scale models of steel beam with web openings have been tested in the experimental investigation. The finite element method has been used to predict their entire response to increasing values of external loading until they lose their load carrying capacity. FE model of each specimen that is utilized in the experimental studies is carried out. These models are used to simulate the experimental work to verify test results and to investigate the nonlinear behaviour of failure modes such as local buckling, lateral torsional buckling, web-post buckling, shear buckling and Vierendeel bending of beams.