• Title/Summary/Keyword: Bifurcation Buckling

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Buckling Analysis of the Large Span Spatial Structures by Modal Analysis (Modal Analysis법에 의한 무주대공간 구조물의 좌굴해석)

  • 한상을;권택진
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1996.10a
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    • pp.195-201
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    • 1996
  • This paper is mainly forcused on the application of modal analysis In analyze the geometrically non-linear buckling behaviors of large span spatial structures, and the evaluation of each eigen mode affected post-buckling behaviors and buckling loads. Modal analysis is applied . to derivation of the system matrices transforming actual displacement space into generalized coordinates space represented by coefficients multiplied in the linear combination of eigen modes which are independent and orthogonal each other. By using modal analysis method, it will be expected to save the calculating time by computer extremely. For example, we can obtain the satisfactorily good results by using about 7% of total eigen modes only in case of single layer latticed dome. And we can decrease the possibility of divergence on the bifurcation point in the calculation of post-buckling path. Arc-length method and Newton-Raphson iteration method are used to calculate the nonlinear equilibrium path.

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A study of the Snapping investigations of Seoul Southwest Baseball Dome (서울 서남권 돔 야구장의 Snapping 검토에 관한 연구)

  • Kim, Seung-Deog;Kim, Nam-Seok
    • Journal of Korean Association for Spatial Structures
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    • v.10 no.4
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    • pp.133-140
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    • 2010
  • This paper studies on the instability behaviour of the Seoul southwest baseball dome. The nonlinear Snapping phenomenon of the structure is investigated about the load mode by the design load of analysis structure and these combined loads. The initial imperfection obtains the buckling mode through the eigenvalue analysis of the tangential stiffness matrix and uses this for the nonlinear analysis. However, the buckling of members or the local buckling, and etc don't consider in the research range of this research task. Also it is limited the overall buckling phenomenon.

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Scale-dependent buckling of embedded thermo-electro-magneto-elastic cylindrical nano-shells with different edge conditions

  • Yifei Gui;Honglei Hu
    • Advances in nano research
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    • v.16 no.6
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    • pp.601-613
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    • 2024
  • A new analytical buckling solution of a thermo-electro-magneto-elastic (TEME) cylindrical nano-shell made of BiTiO3-CoFe2O4 materials is obtained based on Hamiltonian approach. The Winkler and Pasternak elastic foundations as well as thermo-electro-magneto-mechanical loadings are applied, and two different types of edge conditions are taken into the investigation. According to nonlocal strain gradient theory (NSGT) and surface elasticity theory in conjunction with the Kirchhoff-Love theory, governing equations of the nano-shell are acquired, and the buckling bifurcation condition is obtained by adopting the Navier's method. The detailed parameter study is conducted to investigate the effects of axial and circumferential wave numbers, scale parameters, elastic foundations, edge conditions and thermo-electro-magnetic loadings on the buckling behavior of the nano-shell. The proposed model can be applied in design and analysis of TEME nano components with multi-field coupled behavior, multiple edge conditions and scale effect.

Energy approach for dynamic buckling of shallow fixed arches under step loading with infinite duration

  • Pi, Yong-Lin;Bradford, Mark Andrew;Qu, Weilian
    • Structural Engineering and Mechanics
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    • v.35 no.5
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    • pp.555-570
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    • 2010
  • Shallow fixed arches have a nonlinear primary equilibrium path with limit points and an unstable postbuckling equilibrium path, and they may also have bifurcation points at which equilibrium bifurcates from the nonlinear primary path to an unstable secondary equilibrium path. When a shallow fixed arch is subjected to a central step load, the load imparts kinetic energy to the arch and causes the arch to oscillate. When the load is sufficiently large, the oscillation of the arch may reach its unstable equilibrium path and the arch experiences an escaping-motion type of dynamic buckling. Nonlinear dynamic buckling of a two degree-of-freedom arch model is used to establish energy criteria for dynamic buckling of the conservative systems that have unstable primary and/or secondary equilibrium paths and then the energy criteria are applied to the dynamic buckling analysis of shallow fixed arches. The energy approach allows the dynamic buckling load to be determined without needing to solve the equations of motion.

Nonlinear Buckling and Imperfection Sensitivity Analyses of Shell Structures (셸 구조물의 비선형좌굴 및 결함민감도 해석)

  • 원종진
    • Journal of the KSME
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    • v.33 no.7
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    • pp.614-627
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    • 1993
  • 좌굴하기 쉬운 구조물을 설계할 때는 반드시 좌굴특성에 대한 어떤 직관을 가져야 한다. 이글의 목적은 셸 구조물이 비선형붕괴(nonlinear collapse), 분기좌굴(bifurcation buckling) 또는 이들 모드의 조합에 의해서 어떻게 좌굴될 것인가에 대한 감각을 전하는데 있다. 이 불안정에 대한 직관적 이해는 보강되고 여러 요소들로 조립되며 분지셸(branched shell)을 갖거나 복잡한 벽구 조를 갖는 실제 셸 구조물 등의 많은 예에 의해서 얻어질 수 있다. 이 글에서는 수식의 개발이 아니라 불안정의 예측에 주안점을 두고 있으며, 큰 처짐과 소성의 조합에 의해 발생되는 비선 형좌굴과 결함민감도가 특히 강조된다. 또한 최적화된 구조물의 국부 및 전체 불안정, 좌굴모드의 상호작용, 그리고 결함민감도(imperfection sensitivity) 등이 예시된다.

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Lateral-torsional buckling of prismatic and tapered thin-walled open beams: assessing the influence of pre-buckling deflections

  • Andrade, A.;Camotim, D.
    • Steel and Composite Structures
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    • v.4 no.4
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    • pp.281-301
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    • 2004
  • The paper begins by presenting a unified variational approach to the lateral-torsional buckling (LTB) analysis of doubly symmetric prismatic and tapered thin-walled beams with open cross-sections, which accounts for the influence of the pre-buckling deflections. This approach (i) extends the kinematical assumptions usually adopted for prismatic beams, (ii) consistently uses shell membrane theory in general coordinates and (iii) adopts Trefftz's criterion to perform the bifurcation analysis. The proposed formulation is then applied to investigate the influence of the pre-buckling deflections on the LTB behaviour of prismatic and web-tapered I-section simply supported beams and cantilevers. After establishing an interesting analytical result, valid for prismatic members with shear centre loading, several elastic critical moments/loads are presented, discussed and, when possible, also compared with values reported in the literature. These numerical results, which are obtained by means of the Rayleigh-Ritz method, (i) highlight the qualitative differences existing between the LTB behaviours of simply supported beams and cantilevers and (ii) illustrate how the influence of the pre-buckling deflections on LTB is affected by a number of factors, namely ($ii_1$) the minor-to-major inertia ratio, ($ii_2$) the beam length, ($ii_3$) the location of the load point of application and ($ii_4$) the bending moment diagram shape.

Thermal post-buckling analysis of graphene platelets reinforced metal foams beams with initial geometric imperfection

  • Gui-Lin She;Yin-Ping Li;Yujie He;Jin-Peng Song
    • Computers and Concrete
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    • v.33 no.3
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    • pp.241-250
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    • 2024
  • This article investigates the thermal and post-buckling problems of graphene platelets reinforced metal foams (GPLRMF) beams with initial geometric imperfection. Three distribution forms of graphene platelet (GPLs) and foam are employed. This article utilizes the mixing law Halpin Tsai model to estimate the physical parameters of materials. Considering three different boundary conditions, we used the Euler beam theory to establish the governing equations. Afterwards, the Galerkin method is applied to discretize these equations. The correctness of this article is verified through data analysis and comparison with the existing articles. The influences of geometric imperfection, GPL distribution modes, boundary conditions, GPLs weight fraction, foam distribution pattern and foam coefficient on thermal post-buckling are analyzed. The results indicate that, perfect GPLRMF beams do not undergo bifurcation buckling before reaching a certain temperature, and the critical buckling temperature is the highest when both ends are fixed. At the same time, the structural stiffness of the beam under the GPL-A model is the highest, and the buckling response of the beam under the Foam-II mode is the lowest, and the presence of GPLs can effectively improve the buckling strength.

An Introduction of Bifurcation Algorithm into the Elastic-Plastic Finite Element Analysis (분기좌굴이론의 탄소성 유한요소법에의 적용)

  • 김종봉;양동열;윤정환
    • Transactions of Materials Processing
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    • v.9 no.2
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    • pp.128-139
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    • 2000
  • Wrinkling is one of the major defects in sheet metal products and may be also attributable to the wear of the tool. The initiation and growth of wrinkles are influenced by many factors such as stress state, mechanical properties of the sheet material, geometry of the body, and contact condition. It is difficult to analyze the wrinkling initiation and growth considering the factors because the effects of the factors are very complex and the wrinkling behavior may show a wide variation for small deviations of the factors. In this study, the bifurcation theory is introduced for the finite element analysis of wrinkling initiation and growth. All the above mentioned factors are conveniently considered by the finite element method. The finite element formulation is based on the incremental deformation theory and elastic-plastic elements considering the planar anisotropy of the sheet metal. The proposed method is verified by employing a column buckling problem. And then, the initiation and growth of wrinkling in deep drawing of cylindrical cup are analyzed.

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A Study on the Bifurcation Characteristics of Hybrid Cable Domes under Axisymmetric Load (축대칭 하중을 받는 Hybrid 케이블 돔의 Bifurcation 특성에 관한 연구)

  • 김승덕;백인성;김형석
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2003.10a
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    • pp.277-284
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    • 2003
  • One of important problem, in large space structure, is to overcome the self-weight of roof structure. This problem can be solved with using tension members effectively. Thus the rapid progress of hybrid structure, that makes effective use of the means of settling, has a good effect on realizing the large space. These systems of hybrid structure have the advantages of light weight and its own internal redundancy, but are occurred unstable phenomenon such as bifurcation or snap-through buckling, when the load level is come to the critical point. Among the hybrid structure, cable dome is shown the strong nonlinearity of unstable phenomenon in accordance with the external force. Therefore, the purpose of this study is to analyze and verify comparatively the unstable phenomenon of the Geiger and Flower type cable dome structures under axismmetric load.

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Behavior Analysis of Laminated Composite Cylindrical Shells with Prebuckling (전좌굴을 고려한 복합적층원통셸의 거동해석)

  • 이종선
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.9 no.5
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    • pp.150-156
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    • 2000
  • The objective of this study is to investigate effects of prebuckling on the buckling of laminated composite cylindrical shells. Axial compression and lateral pressure are considered for laminated composite cylindrical shells with the ratios of length to radius. The shell walls are made of a laminate with several symmetric ply orientations. The study was made using finite difference energy method, utilizing the nonlinear bifurcation branch with nonlinear prebuckling displacements. The results are compared to the buckling loads determined when membrane prebuckling displacements are considered. Review the influence of nonlinear prebuckling for the buckling loads, the difference between the actual and classical buckling loads are increased as the increments with the ratios of length to radius, for which is applied the axial compression, but almost same for the lateral pressure.

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