• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.3
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• pp.321-328
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• 2000

An improved formulation of thin-wailed curved beams with variable curvatures based on displacement field considering the second order terms of finite semitangential rotations is presented. From linearized virtual work principle by Vlasov's assumptions, the total potential energy is derived and all displacement parameters and the warping functions are defined at cendtroid axis. In developing the thin-walled curved beam element having eight degrees of freedom per a node, the cubic Hermitian polynomials are used as shape functions. In order to verify the accuracy and practical usefulness of this study, free vibrations and buckling analyses of parabolic and elliptic arche shapes with mono-symmetric sections are carried out and compared with the results analyzed by ABAQUS' shell element.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.10a
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• pp.99-104
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• 2001

Thermally induced vibration response of solar array is investigated. The solar array model consists of composite thin walled beam and solar blanket, spreader bar. The composite thin walled beam incorporates a number of nonclassical effects of transverse shear, primary and secondary warping, rotary inertia and anisotropy of constituent materials. The solar blanket is a membrane subjected to uniform tension in the z direction. The spreader bar is a rigid member. A coupled thermal structure analysis that includes the effects of structural deformations on heating and temperature gradient is investigated. A stability criterion given in parameters for establishes the conditions for thermal flutter.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.202-206
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• 2005

Most of studies on the open section composite beams are confined to the thin composite beams. There are some works focused on the thick composite beams but they are limited only to closed section beams. Therefore, it is required to develop an appropriate model to analyze the thick open section composite beams. In this study, the cantilever beams of two specific lay-up configurations are considered which are the circumferentially asymmetric stiffness (CAS) and circumferentially uniform stiffness (CUS) beams. Under the torsional loading, loading induced deformations are obtained for the thick beams using the suggested model. The model includes coupled stiffness and secondary warping effects. The results are compared with those obtained using thin beam model to observe the thickness effects. Those results are also compared with the finite element analysis results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.1
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• pp.100-114
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• 1996

In this paper, a new thin-walled beam finite elcment is developed to overmome the difficulties in the analysis of real structures by existing beam elements. The element is formulated by extending Benscoter's assumption and also by adopting the concept of the curvature-based element. It is applicable to the analysis of the beams with arbitrary cross-sectional shapes. The results obtained show that the element is locking-free and the accuracy of the finite element solutions is remarkably improved.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.161-164
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• 2000

In this paper, a finite element structural analysis for thin-walled open-section composite beams with elastic couplings has been performed. The analysis includes the effects of transverse shear across beam sections, torsion warping and constrained warping. Reissner's semi-complementary energy functional is used to obtain the beam st illness coefficients The bending and torsion related warpings and the shear correct ion factors are obtained as part of the analysis. The resulting theory describes the beam kinematics in terms of the axial, flap and lag bending, flap and lag shear, torsion and torsion-warping deformations. The static response has been validated against finite element predict ions, closed form solutions, and experimental data for rectangular sol id and I-beams with elastic couplings. The free vibration results are also compared with available literature.

• Journal of Korean Association for Spatial Structures
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• v.10 no.4
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• pp.123-132
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• 2010

To overcome the drawback of currently available curved beam theories having non-symmetric thin-walled cross sections, a curved beam theory based on centroid-shear center formulation is presented for the spatially coupled free vibration and elastic analyses. For this, the displacement field is expressed by introducing displacement parameters defined at the centroid and shear center axes, respectively. Next the elastic strain and kinetic energies considering the thickness-curvature effect and the rotary inertia of curved beam are rigorously derived by degenerating the energies of the elastic continuum to those of curved beam. In order to illustrate the validity and the accuracy of this study, FE solutions using the Hermitian curved beam elements are presented and compared with the results by centroid formulation, previous research and ABAQUS's shell elements.

• Composites Research
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• v.23 no.6
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• pp.47-54
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• 2010

Thermal vibration characteristics of a thin walled composite beam attached on spacecraft are investigated in this paper. The composite beam is assumed to have a thin CUS(circumferentially uniform stiffness) wall and modeled with several composite materials which are already space qualified such as T300/Epoxy, YS90AEpoxy. Steady state angle and peak to peak error in spacecraft attitude angle and tip displacement of composite beams are evaluated as a performance index for thermal vibration characteristics. Evaluation results shows that composite beam made out of YS90A has nearly 2 times better than T300 in terms of peak to peak attitude error angle.

• Steel and Composite Structures
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• v.7 no.1
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• pp.53-70
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• 2007

This paper presents a analysis of the problem of optimal design of the beams with two I-type cross section shapes. These types of beams are simply supported and subject to pure bending. The strength and stability conditions were formulated and analytically solved in the form of mathematical equations. Both global and selected types of local stability forms were taken into account. The optimization problem was defined as bicriteria. The cross section area of the beam is the first objective function, while the deflection of the beam is the second. The geometric parameters of cross section were selected as the design variables. The set of constraints includes global and local stability conditions, the strength condition, and technological and constructional requirements in the form of geometric relations. The optimization problem was formulated and solved with the help of the Pareto concept of optimality. During the numerical calculations a set of optimal compromise solutions was generated. The numerical procedures include discrete and continuous sets of the design variables. Results of numerical analysis are presented in the form of tables, cross section outlines and diagrams. Results are discussed at the end of the work. These results may be useful for designers in optimal designing of thin-walled beams, increasing information required in the decision-making procedure.

• Aerospace Engineering and Technology
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• v.8 no.2
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• pp.149-159
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• 2009

This paper deals with an analytical study on the aileron reversal characteristics of anisotropic composite aircraft wings modelled as thin-walled beam and having extension-twist structural couplings caused by Circumferentially Uniform Stiffness (CUS) layup scheme. For a study on the aileron reversal of CUS composite wings, it is essential to consider the following effects such as extension-twist structural coupling, wing aspect ratio, and ratio of span-wise and chord-wise length of aileron to wing, initial angle of attack, and sweep angle, etc. The results on the aileron reversal could have a significant role in more efficient designs of thin-walled composite wing aircraft for which this aeroelastic instability is one of the most critical ones.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.12
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• pp.1192-1200
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• 2009

This paper deals with an analytical study on the aileron reversal characteristics of anisotropic composite aircraft wings modelled as thin-walled beam and having bending-torsion structural couplings caused by Circumferentially Asymmetric Stiffness layup scheme. For a study on the aileron reversal of CAS composite wings, it is essential to consider the following effects such as warping restraint, transverse shear flexibility, bending-twist structural coupling, wing aspect ratio, ratio of span-wise and chord-wise length of aileron to wing, and sweep angle, etc. The results on the aileron reversal could have a significant role in more efficient designs of thin-walled composite wing aircraft for which this aeroelastic instability is one of the most critical ones.