• Title/Summary/Keyword: Thin Shell

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A Study on the Buckling and Ultimate Strength for Cylindrically curved plate subject to combined load (조합하중을 받는 원통형 곡판구조의 좌굴 및 최종강도 거동에 관한 연구)

  • Oh, Young-Cheol;Ko, Jae-Yong;Lee, Kyoung-Woo
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2007.12a
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    • pp.25-26
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    • 2007
  • Ship are typically thin-walled structures and consists of stiffened plate structure by purpose of required design load and weight reduction etc. Also, a hull structural characteristics are often used in structures with curvature at deck plating with camber, side shell plating at fore and aft parts and bilge circle parts, It have been believed that these structures can be modelled fundamentally by a part of cylinder. Structural component with curvature subjected to combined loading regimes and complex boundary conditions, which can potentially collapse due to buckling. Hence, for more rational and safe design of ship structures, it is crucial importance to better understand the interaction relationship of the buckling and ultimate strength for cylindrically curved plate under these load components. In this study, the ultimate strength characteristic of curved plate under combined load(lateral pressure load + axial compressive load) are investigated through using FEM series analysis with varying geometric panel properties.

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Calculation of Stiffnesses Properties for Composite Box-Beams with Elastic Couplings (구조연성을 고려한 복합재료 상자형 보의 강성계수 예측에 관한 연구)

  • 정성남;동경민
    • Composites Research
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    • v.14 no.6
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    • pp.9-15
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    • 2001
  • In the present work, a linear static analysis is presented for thin-walled prismatic box-beams made of generally anisotropic materials. A mixed beam theory has been used to model and carry out the analysis. Several different constitutive assumptions for the shell-wall of the beam section are assessed into the beam formulation. Simple layup cases of box-beams representing bending-torsion or extension-torsion coupled configuration have been considered and tested to clearly show the effects of elastic couplings of the beam. A detailed finite element structural analysis using the MSC/NASTRAN has been carried out to validate the current analytical results. Numerical results show that appropriate assumptions for the constitutive relations are important and crucial for the accurate prediction of beam stiffness constants and also thor the beam behavior.

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Analysis of Wrinkling for Creased Thin Membrane (접힌 자국이 있는 멤브레인의 주름 거동 해석)

  • Woo, Kyeong-Sik
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.36 no.9
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    • pp.851-858
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    • 2008
  • In this paper, the wrinkling behavior of vertically creased corner-loaded square membranes was studied using geometrically nonlinear post-buckling analysis. The membranes were modeled using shell elements, and the meshes were seeded with semi-random geometrical imperfection to instigate the buckling deformation. A pristine and creased membranes with various initial deployment angles were considered in the analyses and the results were compared. Results showed that local wrinkles initiated near the corner where the higher load was applied, which grew to form a single diagonal global wrinkle as the load ratio increased. It was also found that the local wrinkle initiation and the global wrinkle formation were significantly dependent on the initial deployment angles.

A continuum mechanics based 3-D beam finite element with warping displacements and its modeling capabilities

  • Yoon, Kyungho;Lee, Youngyu;Lee, Phill-Seung
    • Structural Engineering and Mechanics
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    • v.43 no.4
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    • pp.411-437
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    • 2012
  • In this paper, we propose a continuum mechanics based 3-D beam finite element with cross-sectional discretization allowing for warping displacements. The beam element is directly derived from the assemblage of 3-D solid elements, and this approach results in inherently advanced modeling capabilities of the beam element. In the beam formulation, warping is fully coupled with bending, shearing, and stretching. Consequently, the proposed beam elements can consider free and constrained warping conditions, eccentricities, curved geometries, varying sections, as well as arbitrary cross-sections (including thin/thick-walled, open/closed, and single/multi-cell cross-sections). We then study the modeling and predictive capabilities of the beam elements in twisting beam problems according to geometries, boundary conditions, and cross-sectional meshes. The results are compared with reference solutions obtained by analytical methods and solid and shell finite element models. Excellent modeling capabilities and solution accuracy of the proposed beam element are observed.

Nonlinear free vibration of heated corrugated annular plates with a centric rigid mass

  • Wang, Yong-Gang;Li, Dan;Feng, Ze-Jun
    • Structural Engineering and Mechanics
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    • v.34 no.4
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    • pp.491-505
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    • 2010
  • A computational analysis of the nonlinear free vibration of corrugated annular plates with shallow sinusoidal corrugations under uniformly static ambient temperature is examined. The governing equations based on Hamilton's principle and nonlinear bending theory of thin shallow shell are established for a corrugated plate with a concentric rigid mass at the center and rotational springs at the outer edges. A simple harmonic function in time is assumed and the time variable is eliminated from partial differential governing equations using the Kantorovich averaging procedure. The resulting ordinary equations, which form a nonlinear two-point boundary value problem in spatial variable, are then solved numerically by shooting method, and the temperature-dependent characteristic relations of frequency vs. amplitude for nonlinear vibration of heated corrugated annular plates are obtained. Several numerical results are presented in both tabular and graphical forms, which demonstrate the accuracy of present method and illustrate the amplitude frequency dependence for the plate under such parameters as ambient temperature, plate geometry, rigid mass and elastic constrain.

Behavior of Segmented Composites Using General Mortar under Static and Impact Loading (일반 모르타르를 이용한 분절 복합체의 정하중 및 충격하중 실험)

  • Kim, Youl-Hee;Min, Kyung-Hwan;Lee, Jae-Seong;Yoon, Young-Soo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.33-36
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    • 2008
  • It is generally known that a shell in the form of layered structures stacked up thin elements by organic adhesives has high resistance capacity against static and impact loading. The complex materials such as these diversified layered structures are more reliable and efficient to the impact loading than the single material. In this study, the segmented composites in the shape of a beam were made, using mortar and concrete block and tested under static and impact loading in order to develop the complex materials in the form of layered structures as the segmented composites to resist impact loading. And it compared to the normal concrete beams having the same compressive strength to evaluate the differences in their performance and failure modes.

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Model Simulations for the Dust-Scattered Far-Ultraviolet in the Orion-Eridanus Superbubble

  • Jo, Young-Soo;Min, Kyoung-Wook;Lim, Tae-Ho;Seon, Kwang-Il
    • The Bulletin of The Korean Astronomical Society
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    • v.37 no.1
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    • pp.73.1-73.1
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    • 2012
  • We present the results of dust scattering simulations carried out for the Orion Eridanus Superbubble region by comparing them with observations made in the far-ultraviolet. The albedo and the phase function asymmetry factor (g-factor) of interstellar grains were estimated as well as the distance and thickness of the dust layers. The results are: 0.39-0.45 for the albedo and 0.25-0.65 for the g-factor, in good agreement with previous determinations and theoretical predictions. The distance of the assumed single dust layer, modeled for the Orion Molecular Cloud Complex, was estimated to be -110 pc and the thickness ranged from -130 at the core to -50 pc at the boundary for the region of the present interest, implying that the dust cloud is located in front of the Superbubble. The simulation result also indicates that a thin (-10 pc) dust shell surrounds the inner X-ray cavities of hot gas at a distance of -70-90 pc.

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"Buildings Without Walls:" A Tectonic Case for Two "First" Skyscrapers

  • Leslie, Thomas
    • International Journal of High-Rise Buildings
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    • v.9 no.1
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    • pp.53-60
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    • 2020
  • "A practical architect might not unnaturally conceive the idea of erecting a vast edifice whose frame should be entirely of iron, and clothing the frame--preserving it--by means of a casing of stone…that shell must be regarded only as an envelope, having no function other than supporting itself..." --Viollet-le-Duc, 1868. Viollet-le-Duc's recipe for an encased iron frame foresaw the separation of structural and enclosing functions into discrete systems. This separation is an essential characteristic of skyscrapers today, but at the time of his writing cast iron's brittle nature meant that iron frames could not, on their own, resist lateral forces in tall structures. Instead, tall buildings had to be braced with masonry shear walls, which often also served as environmental enclosure. The commercial availability of steel after the 1880s allowed for self-braced metal frames while parallel advances in glass and terra cotta allowed exterior walls to achieve vanishingly thin proportions. Two Chicago buildings by D.H. Burnham & Co. were the first to match a frame "entirely of iron" with an "envelope" supporting only itself. The Reliance Building (1895) was the first of these, but the Fisher Building (1896) more fully exploited this new constructive typology, eschewing brick entirely, to become the first "building without walls," a break with millennia of tall construction reliant upon masonry

Comparison of UNDEX Whipping Response of Hull Girder according to Modeling Methods (해석모델링 방법에 따른 선체거더의 수중폭발 휘핑응답 비교)

  • Kwon, Jeong-Il;Chung, Jung-Hoon;Lee, Sang-Gab
    • Journal of the Society of Naval Architects of Korea
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    • v.42 no.6 s.144
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    • pp.631-636
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    • 2005
  • One and three dimensional whipping response analyses of a naval surface combatant subjected to an underwater explosion bubble pulse were carried out to compare the efficiency and accuracy according to the modeling methods. In 1-D analysis, program UNDEXWHIP developed by KIMM was used, which is based on the thin-walled Timoshenko's beam theory and on the modal analysis method using wetted vibratory modes of the hull girder. In 3-D analysis, three finite element models were suggested using LS-DYNA/USA code, such as 3-D beam model considering geometric shape of wetted side shell, coarse and fine 3-D F.E. models. Through the comparison of results from the 1-D and 3-D analyses, it could be confirmed that 1-D analysis result is in good agreement with 3-D analysis ones, and that fine 3-D F.E. model, shock analysis one, is also used both in the shock response and whipping response analyses for the analyst effort and time savings.

Pan-shaped Spray Characteristics of GDI High Pressure Slit Nozzle Injector (가솔린 직접분사식 고압 슬릿 노즐 분사기의 팬형 분무 특성 고찰)

  • Song, Bhum-Keun;Kim, Won-Tae;Kang, Shin-Jae
    • Transactions of the Korean Society of Automotive Engineers
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    • v.13 no.6
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    • pp.70-76
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    • 2005
  • A new stratified charge combustion system has been introduced and developed for GDI engines. Before this new GDI system, the stratified mixture was formed by a high pressure swirl injector. But, the special feature of new system is employed of a thin fan-shaped fuel spray formed by a slit type nozzle. Also, this system has been adopted a shell-shaped piston cavity. We made high pressure gasoline injection system and investigated the fan-shaped spray characteristics such as spray tip penetration, spray angle, SMD and velocities of droplets using PDPA(Phase Doppler Particle Analyzer) system and spray visualization system to obtain the concept of the new design and the fundamental data for the next generation GDI system. The experiment was performed at the injection pressures of 5 and 9MPa under the atmospheric condition.