• 오토저널
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• 제8권2호
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• pp.51-64
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• 1986

There has been considerable interest over the last twenty years in the subject of the elastic properties of the cord-rubber laminate. This has been due to the rather intensive study of the composites materials characteristics brought about by the increased use of rigid composites materials characteristics brought about by the increased use of rigid composites in many structural applications. The object of this study is to obtain the natural frequencies and modes of the simply supported cord-rubber laminate plates prior to the study on the analysis of the dynamic properties of the pneumatic tire. To obtain these natural frequencies and modes, the 12 degrees of freedom orthotropic rectangular plate finite elements are developed. By using classical lamination theory, the stress-strain relations are represented. The governing equation for the finite element is derived by energy method. To find the natural frequencies and modes, he eigenvalues and corresponding eigenvectors are computed by the well known Jacobi power method. In order to verify the capability of this present finite element, the results of the specially orthotropic plate and the angle-ply laminate plate are compared with the analytical solution. The analytical and numberical results are in good agreement. The following problems of the simply supported plate are analyzed by the present finite element. a) the natural frequencies and mode shapes of the cord-rubber laminate plate for various aspect ratio. b) The natural frequencies and mode shapes of the orthotropic plate with the rectangular hole in its center.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 봄 학술발표회논문집
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• pp.51-58
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• 2000

Lateral buckling behavior of laminated composite thin-walled I-section beams subjected to bending moment is investigated by applying the nonlinear anisotropic thin-walled beam theory. The constituent laminated thin-walled elements of I-section are assumed to be symmetrically laminated. The bending, twisting, and warping stiffnesses of the cross section are obtained based on the definitions of these stiffnesses In the thin-walled anisotropic beam theory In numerical examples, singly-symmetric I-beams with specially orthotropic, quasi-isotropic, angle-plys and various boundary conditions are considered. To validate the proposed theoretical approach, present analytical solutions are compared with three dimensional finite element solutions.

• Structural Engineering and Mechanics
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• 제90권4호
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• pp.391-401
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• 2024

The present study focuses on the effect of extension-bending coupling on the elastic stability (buckling) of laminated composite plates. These plates will be loaded under uni-axial or bi-axial in-plane mechanical loads, especially in the orthotropic or anti-symmetric cross-angle cases. The main objective is to find a limit where we can approximate the elastic stability behavior of angularly crossed anti-symmetric plates by the simple behavior of specially orthotropic plates. The contribution of my present study is to predict the explicit effect of extension-flexion coupling on the elastic stability of this type of panel. Critically, a parametric study is carried out, involving the search for the critical buckling load as a function of deformation mode, aspect ratio, plate anisotropy ratio and finally the study of the effect of lamination angle and number of layers on the contribution of extension-flexure coupling in terms of plate buckling stability. We use first-order shear deformation theory (FSDT) with a correction factor of 5/6. Simply supported conditions along the four boundaries are adopted where we can develop closed-form analytical solutions obtained by a Navier development.

• 대한기계학회논문집
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• 제18권6호
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• pp.1520-1534
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• 1994

A new analytical method for the prediction of the buckling behavior of laminated plates consisting of layers having different properties in tension and compression, so called bimodulus, is proposed in this paper. Buckling analysis of bimodular composite laminated paltes are performed with the results reduced from plate bending analysis. The governing equations of bimodular plates are based on the first shear deformation theory. As a case study, bending and buckling of simply supported, multilayered, symmetric, antisymmtric, and specially orthotropic laminates under uniformly distributed lateral load for bending analysis and in-plane load for buckling are considered. The results of the bending analysis are compared with the previous papers. Then, the fundamental critical buckling loads and buckling modes are calculated for the various bimodular composite rectangular thin plates.

• Coupled systems mechanics
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• 제13권2호
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• pp.95-113
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• 2024

In this paper, we will analyse the thermo-elastic behavior of the plate element of a structure arranged in a climatically aggressive environment (extreme temperature), we use a refined four-variable thick plate theory to take the shear effect into consideration, the proposed theory less computationally expensive and more accurate so that it incorporates the shear effect into the formulation. The plate is assumed to be simply supported on its four edges, so exact (closed-form) solutions are found according to the Navier expansion, and the governing stability equations and associated boundary conditions of the problem are obtained via the virtual works principle. The plate studied ismade of laminated composite materials, so a parametric study is needed to see the effect of different types of parameters and coupling on the critical temperature value causing thermo-elastic instability of the plate and also on the natural frequency of free vibration, as well as for other parameters such as anisotropy, slenderness and aspect ratio of the plate and finally the lamination angle. Numerical results are obtained for specially orthotropic and antisymmetrical plates and are compared with those obtained by othertheoriesin the literature to validate the analysis approach used.

• Structural Engineering and Mechanics
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• 제90권6호
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• pp.601-610
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• 2024

Free vibration of layered conical shell frusta of thickness filled with fluid is investigated. The shell is made up of isotropic or specially orthotropic materials. Three types of thickness variations are considered, namely linear, exponential and sinusoidal along the radial direction of the conical shell structure. The equations of motion of the conical shell frusta are formulated using Love's first approximation theory along with the fluid interaction. Velocity potential and Bernoulli's equations have been applied for the expression of the pressure of the fluid. The fluid is assumed to be incompressible, inviscid and quiescent. The governing equations are modified by applying the separable form to the displacement functions and then it is obtained a system of coupled differential equations in terms of displacement functions. The displacement functions are approximated by cubic and quintics splines along with the boundary conditions to get generalized eigenvalue problem. The generalized eigenvalue problem is solved numerically for frequency parameters and then associated eigenvectors are calculated which are spline coefficients. The vibration of the shells with the effect of fluid is analyzed for finding the frequency parameters against the cone angle, length ratio, relative layer thickness, number of layers, stacking sequence, boundary conditions, linear, exponential and sinusoidal thickness variations and then results are presented in terms of tables and graphs.

• 한국구조물진단유지관리공학회 논문집
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• 제11권1호
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• pp.77-84
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• 2007

본 논문에서는 복합재료로 만들어진 단순지지된 샌드위치 슬래브 교량의 설계 방법을 제시하고자 한다. 거더나 가로보를 포함한 대부분의 교량시스템에서 교량 상판은 특별직교이방성판으로 거동한다. 이러한 단면을 갖는 시스템은 Navier 해법이나 Levy 해법 형태와는 다른 경계조건 또는 불규칙한 단면을 갖게 되어 해석적 해법을 얻기가 쉽지 않다. 이러한 문제를 해석하기 위하여 유한차분법이 이용되었다. 복합재료로 이루어진 교량을 설계하기위하여, 단면은 가장 경제적이면서 응력에 유리한 폼코어 형태를 채택하였고, 응력을 산출함에 있어서는 유한차분법 프로그램을 이용하였다. 복합신소재 특수기술자의 실험을 기초로 질량이 증가에 따른 파이버의 인장강도 감소를 나타내는 공식을 도출하였다. 이 공식으로부터 치수 증가에 따른 인장강도 감소량을 구 할 수 있다. 파괴강도는 Tasi-Wu의 파괴강도이론을 이용하였다. 파괴강도해석은 본 논문에서 제시하고 있는 인장강도의 감소를 고려하여 제시하였다.

• 한국강구조학회 논문집
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• 제17권3호통권76호
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• pp.317-324
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• 2005

본 연구에서는 3경간연속 탄성지지된 복합슬래브교량을 특별직교이방성 판이론을 응용하여 해석하였다. 불균등단면이나 임의의 경계조건을 가진 보나 타워구조물의 고유진동수를 계산하는 방법을 탄성지지된 3경간 연속 복합슬래브교량에 적용하여 연구하였다. 슬래브 상판은 특별직교이방성 판으로 취급하였다. 진동해석에 필요한 변위의 영향계수는 여러 가지 방법으로 구할 수 있으나 본 논문에서는 유한차분법을 사용하였다. 또한 휨강성에 대한 영향과 기초의 탄성계수에 대한 영향에 대하여 연구하였다.

• 복합신소재구조학회 논문집
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• 제1권2호
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• pp.14-19
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• 2010

건설관련 설계기술자들에게는 첨단 복합신소재 구조에 대한 이론이 너무 어려워서 간단하면서도 쉽게 적용할 수 있는 정확한 방법을 필요로 하고 있다. 몇 가지 섬유 배향각을 가진 적층판은 층수가 증가하면 $D_{16}$, $B_{16}$, $D_{26}$ 및 $B_{26}$ 강성이 감소하게 되어 특별직교이방성 판처럼 거동함을 밝히고, 간단한 공식들을 개발하여 발표한 바 있다. 대부분의 교량이나 건물의 상판은 형상비가 큰 경우가 많은데, 이런 구조물의 평형방정식에 대한 종방향모멘트항(Mx)의 영향은 매우 작아서, 더욱 간단한 해석이 가능하다. 본 논문에서는 복합적층판의 고유진동수에 대한 형상비의 영향을 연구하였으며 이 방법을 사용하면 충분히 정확한 값을 쉽게 산출할 수 있다.