• Structural Engineering and Mechanics
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• v.21 no.5
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• pp.591-620
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• 2005

A general analytical model for thin-walled composite beams with an arbitrary open/(or/and) closed cross section and arbitrary laminate stacking sequence i.e., symmetric, anti-symmetric as well as un-symmetric with respect to the mid plane of the laminate, is developed in the first paper. All the mechanical properties, mechanical centre of gravity and mechanical shear centre of the cross section are defined in the function of the geometry and the material properties of the section. A program "fungen" and "clprop" are developed in Fortran to compute all the mechanical properties and tested for various isotropic sections first and compared with the available results. The locations of mechanical centre of gravity and mechanical shear centre are given with respect to the fibre angle variation in composite beams. Variations of bending and torsional stiffness are shown to vary with respect to the fibre angle orientations.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2191-2201
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• 2000

End effects due to sectional deformations of thin-walled beams with closed cross section are analysed by a one-dimensional theory. In particular, end effects associated with warping (out of plane m otion) and distortion (in plane motion) are investigated. The exact solutions as a vector form are newly derived to reveal slowly-decaying nature of the end effects in a thin-walled beam loaded by a couple. Several examples of thin-walled beams under various loading conditions indicate that the local end effect zone due to warping and distortion is approximately ten times the typical beam width.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.194-197
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• 2005

In this work, a mixed beam approach is performed to identify the transverse shear behavior of thin-walled composite beams with closed cross-sections. The analytical model includes the effects of elastic couplings, shell wall thickness, and torsion warping. The distributions of shear flow across the section as well as the shear correction coefficients are obtained in a closed form in the beam formulation. The influence of transverse shear deformation on the static behavior of closed cross-section composite beams is also investigated in the analysis

• Journal of Korean Society of Steel Construction
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• v.14 no.1
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• pp.41-49
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• 2002

An efficient algorithm automatically determining cross sectional properties of thin-walled beams is developed using the minimum information about geometry of the cross section. This scheme is applied to automatic calculation of normal and shear stress distribution corresponding to stress resultants as well as sectional constants for complex open and closed thin-walled sections. Numerical examples evaluating section constants and stress distributions is presented and compared with the available reference's results.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.10a
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• pp.369-376
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• 2000

For the general loading condition and boundary condition, it is very difficult to obtain closed-form solutions for buckling loads and natural frequencies of thin-walled structures because its behaviour is very complex due to the coupling effect of bending and torsional behaviour. Consequently most of previous finite element formulations introduced approximate displacement fields using shape functions as Hermitian polynomials, isoparametric interpoation function, and so on. The purpose of this study is to calculate the exact displacement field of a thin-walled straight beam element with the non-symmetric cross section and present a consistent derivation of the exact dynamic stiffness matrix. An exact dynamic element stiffness matrix is established from Vlasov's coupled differential equations for a uniform beam element of non-symmetric thin-walled cross section. This numerical technique is accomplished via a generalized linear eigenvalue problem by introducing 14 displacement parameters and a system of linear algebraic equations with complex matrices. The natural frequencies are evaluated for the non-symmetric thin-walled straight beam structure, and the results are compared with available solutions in order to verify validity and accuracy of the proposed procedures.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.6
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• pp.486-494
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• 2004

This paper addresses the dynamic modeling and closed-loop eigenvibration analysis of composite rotating pretwisted fan blade modeled as non-uniform thin-walled beam with bi-convex cross-section fixed at the certain presetting angle and incorporating piezoelectric induced damping capabilities. The blade model incorporates non-classical features such as transverse shear, rotary inertia and includes the centrifugal and Coriolis force field. A velocity feedback control law relating the piezoelectiriccally induced transversal bending moment at the beam tip with the appropriately selected kinematical response quantity is used and the beneficial effects upon the closed loop eigenvibration of the blade are highlighted.

• Structural Engineering and Mechanics
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• v.10 no.3
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• pp.263-275
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• 2000

In this paper, a core wall structure coupled with connecting beams is discretized and modeled as an equivalent thin-walled member with closed section, while the connecting beams between openings are replaced by an equivalent shear diaphragm. Then, a numerical method (finite member element method, FMEM) for dynamic analysis of the core wall structure is proposed. The numerical method combines the advantages of the FMEM and Vlasov's thin-walled beam theory and the effects of torsion, warping and, especially, the shearing strains in the middle surface of the walls are considered. The results presented in this paper are very promising compared with the ones obtained from finite element method.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.167-171
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• 2005

The thick open section composite beams are used extensively as load carrying members and stiffeners of structural elements. However, most of studies on thick composite beams are limited only to closed section beams. In this study, an open cross-section thick-walled composite beam model which includes coupled stiffness, transverse shear, and warping effects is suggested and the deflections associated with the thick-walled composite beams and thin-walled composite beams are obtained and compared with the finite element analysis results. The correlation between thin and thick walled composite beam was achieved for two different layup configurations which are the circumferentially asymmetric stiffness (CAS) and circumferentially uniform stiffness (CUS) beams.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.187-190
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• 2005

A simple beam model based on a mixed method is proposed for the analysis of thin-walled composite blades with a two-cell airfoil section. A semi-complementary energy functional is used to obtain the beam force-displacement relations. The theory accounts for the effects of elastic couplings, shell wall thickness, warping, and warping restraint. All the kinematic relations as well as the cross-section stiffnesses are evaluated in a closed-form through the current beam formulation. The theory has been applied to two-cell composite blades with extension-torsion couplings and fairly good correlation has been observed in comparison with a detailed analysis and other literature.

• Advances in aircraft and spacecraft science
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• v.1 no.3
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• pp.253-271
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• 2014

A linearised buckling analysis of thin-walled beams is addressed in this paper. Beam theories formulated according to a unified approach are presented. The displacement unknown variables on the cross-section of the beam are approximated via Mac Laurin's polynomials. The governing differential equations and the boundary conditions are derived in terms of a fundamental nucleo that does not depend upon the expansion order. Classical beam theories such as Euler-Bernoulli's and Timoshenko's can be retrieved as particular cases. Slender and deep beams are investigated. Flexural, torsional and mixed buckling modes are considered. Results are assessed toward three-dimensional finite element solutions. The numerical investigations show that classical and lower-order theories are accurate for flexural buckling modes of slender beams only. When deep beams or torsional buckling modes are considered, higher-order theories are required.