• Title/Summary/Keyword: Geometric Non-linearity

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Strength and Crack Growth Computation for Various types of Stringers for Stiffened Panels using XFEM Techniques

  • Krishna, Lok S;Reshma, G;Dattaguru, B
    • International Journal of Aerospace System Engineering
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    • v.7 no.1
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    • pp.7-15
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    • 2020
  • In this paper the crack growth, modeling, and simulation of the stiffened and un-stiffened cracked panels presented using commercially available finite element software packages. Computation of stresses and convergence of stress intensity factor for single edge notch (SEN) specimens carried out using the finite element method (FEM) and extended finite element method (XFEM) and compared with an analytical solution. XFEM techniques like cohesive segment method and LEFM using virtual crack closure technique (VCCT), used for crack growth analysis and presented results for un-stiffened and stiffened panels considering various crack domain. The non-linear analysis considering both geometric and material non-linearity on stiffened panels with various stringers like a blade, L, inverted T and Z sections the results were presented. Arrived at the optimum stringer section type for the considered panel under axial loading from the numerical analysis.

Vibration of an Axially Moving String Coupled between Longitudinal and Transverse Deflections (종방향과 횡방향 변위가 연성된 축방향으로 움직이는 현의 진동)

  • Chung, J.T.;Shin, C.H.;Han, C.S.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.06a
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    • pp.731-736
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    • 2000
  • The vibration of an axially moving string is studied when the string has geometric non-linearity and translating acceleration. Based upon the von karman strain theory, The equation for the longitudinal vibration is linear and uncoupled, while the equation for the transverse vibration is non-linear and coupled between the longitudinal and transverse deflections. The governing equations are discretized by using the Galerkin approximation. With the discretized nonlinear equations, the time responses are investigated by using the generalized-${\alpha}$ method.

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Post-buckling responses of a laminated composite beam

  • Akbas, Seref D.
    • Steel and Composite Structures
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    • v.26 no.6
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    • pp.733-743
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    • 2018
  • This paper presents post-buckling responses of a simply supported laminated composite beam subjected to a non-follower axially compression loads. In the nonlinear kinematic model of the laminated beam, total Lagrangian approach is used in conjunction with the Timoshenko beam theory. In the solution of the nonlinear problem, incremental displacement-based finite element method is used with Newton-Raphson iteration method. There is no restriction on the magnitudes of deflections and rotations in contradistinction to von-Karman strain displacement relations of the beam. The distinctive feature of this study is post-buckling analysis of Timoshenko Laminated beams full geometric non-linearity and by using finite element method. The effects of the fibber orientation angles and the stacking sequence of laminates on the post-buckling deflections, configurations and stresses of the composite laminated beam are illustrated and discussed in the numerical results. Numerical results show that the above-mentioned effects play a very important role on the post-buckling responses of the laminated composite beams.

A load increment method for ductile reinforced concrete (RC) frame structures considering strain hardening effects

  • Gunhan Aksoylu, M.;Girgin, Konuralp
    • Structural Engineering and Mechanics
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    • v.38 no.2
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    • pp.231-247
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    • 2011
  • This study introduces a new load increment method for the ductile reinforced concrete (RC) frame structures by including strain-hardening effects. The proposed method is a nonlinear static analysis technique employed for RC frame structures subjected to constant gravity loads and monotonically increasing lateral loads. The material nonlinearity in RC structural elements is considered by adopting plastic hinge concept which is extended by including the strain hardening as well as interaction between bending moment and axial force. Geometric non-linearity, known as second order effect, is implemented to the method as well.

Nonlinear thermal displacements of laminated composite beams

  • Akbas, Seref D.
    • Coupled systems mechanics
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    • v.7 no.6
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    • pp.691-705
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    • 2018
  • In this paper, nonlinear displacements of laminated composite beams are investigated under non-uniform temperature rising with temperature dependent physical properties. Total Lagrangian approach is used in conjunction with the Timoshenko beam theory for nonlinear kinematic model. Material properties of the laminated composite beam are temperature dependent. In the solution of the nonlinear problem, incremental displacement-based finite element method is used with Newton-Raphson iteration method. The distinctive feature of this study is nonlinear thermal analysis of Timoshenko Laminated beams full geometric non-linearity and by using finite element method. In this study, the differences between temperature dependent and independent physical properties are investigated for laminated composite beams for nonlinear case. Effects of fiber orientation angles, the stacking sequence of laminates and temperature on the nonlinear displacements are examined and discussed in detail.

Dynamic Non-Linear Analysis of Ocean Cables Subjected to Earthquakes (지진력을 받는 해양케이블의 동적 비선형해석)

  • 김남일;신현목
    • Journal of the Earthquake Engineering Society of Korea
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    • v.3 no.2
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    • pp.77-86
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    • 1999
  • In the previous $paper^{(1),(2)}$, a geometrically non-linear finite element formulation of spatial cables subjected to self-weights and support motions was presented using multiple noded cable elements and how to determine the initial equililbrium state of cables was addressed. In this paper, in order to perform dynamic non-linear analysis of ocean cables subjected to support motions and earthquakes, a numerical method to calculate Morison forces and incorporate effects of earthquake motions is presented based on the Newmark method. Challenging example problems are presented in order to investigate dynamic non-linear behaviors of ocean cables subjected to support motions and earthquake loadings.

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The Concept and Analysis of Redundant Information in Space Perception - Focused on the Works of NOX - (공간지각에 있어 잉여정보의 의미와 분석 - NOX의 공간을 중심으로-)

  • Kim, Joo-Mi
    • Korean Institute of Interior Design Journal
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    • v.15 no.6 s.59
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    • pp.77-88
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    • 2006
  • According to critics and architects, non-linear structure is not only an organic form of space, but also a form of space detached from modem style. Accordingly, non-linear structure can be accepted as an alternative to what has remained unsolved by deconstructionist. However, they are criticized for not clarifying the interdependent relationship between non-linearity of space and cognitive structure of human being. They ended up remaining the hypothesis just an intuitive and abstract one. This research began on the basis that their hypothesis is hard to be objectified, and it needs further inquiry. The purpose of this thesis is to explore how the redundant factors constitute non-linear structures of digital media centered space design. Geometric compositions of space structure were analyzed to define what types of redundant factors are contrived in the process of visual information. This study about the visual form, researching the Information Theory, and then offer a quantitative analysis that makes those more objective. Space structure and geometric composition were analyzed to define what types of redundancy are contrived in the process of visual information. In particular, I put higher theoretical emphasis on what characteristics are ensued in the process of structuring spaces than any other subjects. Followings are the conclusion of analysis. First, as a result of examining, we can assume that NOX' space structure is not a chaotic form, but has an operating the form of its own. Second, in case of curvilinear, the structure was found redundancy on mid deviation ratio and discontinuous circular fabric. Although most of their structures appeared complex with a higher coherent constant, they were found to be stable factors because of the low deviation ratio between systems. The amount of surplus information was stable structure as well.

Finite element based post-buckling analysis of refined graphene oxide reinforced concrete beams with geometrical imperfection

  • Mirjavadi, Seyed Sajad;Forsat, Masoud;Yahya, Yahya Zakariya;Barati, Mohammad Reza;Jayasimha, Anirudh Narasimamurthy;Khan, Imran
    • Computers and Concrete
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    • v.25 no.4
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    • pp.283-291
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    • 2020
  • The present paper researches post-buckling behaviors of geometrically imperfect concrete beam resting on elastic foundation reinforced with graphene oxide powders (GOPs) based on finite element method (FEM). Distribution of GOPs are considered as uniform and linearly graded through the thickness. Geometric imperfection is considered as first buckling mode shape of the beam, the GOP reinforced beam is rested in initial position. The material properties of GOP reinforced composite have been calculated via employment of Halpin-Tsai micromechanical scheme. The provided refined beam element verifies the shear deformation impacts needless of any shear correction coefficient. The post-buckling load-deflections relations have been calculated via solving the governing equations having cubic non-linearity implementing FEM. Obtained findings indicate the importance of GOP distributions, GOP weight fraction, matrix material, geometric imperfection, shear deformation and foundation parameters on nonlinear buckling behavior of GOP reinforced beam.

Study on Structural Integrity of Bearingless Main Rotor Hub System of Helicopter (헬리콥터 무베이링 메인 로터 허브 시스템의 구조 건전성에 관한 연구)

  • Lee, Mu-Hyoung;Park, Ill-Kyoung;Kim, Sung-Joon;Hwang, In-Hee;Kim, Tae-Joo
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.20 no.4
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    • pp.50-56
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    • 2012
  • Rotor system is a very important part which produce lift, thrust and control force in helicopter. Component of rotor system must have structural integrity for applied load. The estimation of structural integrity is regarded greatly as important in aerospace field. In this study, the process of structural analysis performed for bearingless main rotor system of helicopter. The composite flexbeam and torque tube of bearingless main rotor are very thick, so 3D layered soild elements of MSC.PATRAN were used to get the finite element analysis results. To estimate structural integrity, non-linear static analysis considering geometric non-linearity is performed. In addition, detailed finete element analysis and non-linear static analysis are performed to consider the stress concentration for fitting effect and contact surface. The estimation process of structural integrity for bearingless main rotor system of helicopter may help the design.

Static Non-linear Finite Element Analysis of Spatial Cable Networks (3차원 케이블망의 초기평형상태 결정 및 정적 비선형 유한요소해석)

  • 김문영;김남일;안상섭
    • Computational Structural Engineering
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    • v.11 no.1
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    • pp.179-190
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    • 1998
  • A geometrically nonlinear finite element formulation of spatial cable networks is presented using two cable elements. Firstly, derivation procedures of tangent stiffness and mass matrices for the space truss element and the elastic catenary cable element are summarized. The load incremental method based on Newton-Raphson iteration method and the dynamic relaxation method are presented in order to determine the initial static state of cable nets subjected to self-weights and support motions. Furthermore, static non-linear analysis of cable structures under additional live loads are performed based on the initial configuration. Challenging example problems are presented and discussed in order to demonstrate the feasibility of the present finite element method and investigate static nonlinear behaviors of cable nets.

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