• Title/Summary/Keyword: open section

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Pre-buckling deflection effects on stability of thin-walled beams with open sections

  • Mohri, F.;Damil, N.;Potier-Ferry, M.
    • Steel and Composite Structures
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    • v.13 no.1
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    • pp.71-89
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    • 2012
  • The paper investigates beam lateral buckling stability according to linear and non-linear models. Closed form solutions for single-symmetric cross sections are first derived according to a non-linear model considering flexural-torsional coupling and pre-buckling deformation effects. The closed form solutions are compared to a beam finite element developed in large torsion. Effects of pre-buckling deflection and gradient moment on beam stability are not well known in the literature. The strength of singly symmetric I-beams under gradient moments is particularly investigated. Beams with T and I cross-sections are considered in the study. It is concluded that pre-buckling deflections effects are important for I-section with large flanges and analytical solutions are possible. For beams with T-sections, lateral buckling resistance depends not only on pre-buckling deflection but also on cross section shape, load distribution and buckling modes. Effects of pre-buckling deflections are important only when the largest flange is under compressive stresses and positive gradient moments. For negative gradient moments, all available solutions fail and overestimate the beam strength. Numerical solutions are more powerful. Other load cases are investigated as the stability of continuous beams. Under arbitrary loads, all available solutions fail, and recourse to finite element simulation is more efficient.

Study on the effect of Post Open laser Lumbar Micro-discectomy on the Cross Section Area of Deep Muscles in Patients (요추부 미세 현미경 레이져 디스크 수술(OLM)이 환자의 심부근육 단면적 크기에 미치는 영향)

  • Kong, Bong-Jun;Kim, Jin-Sang;Min, Dong-Ki
    • PNF and Movement
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    • v.10 no.2
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    • pp.25-31
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    • 2012
  • Purpose : The purpose of this study is to figure out the effects of Open Laser Microdiscectomy(OLM) on deep muscles by comparing multifidus and longissimus muscle size (cross section area; CSA) of pre and post operation. Methods : The subjects consisted of forty patients who had OLM. The data were analyzed with paired t-test comparing left and right deep muscle CSA of pre and post-operation, and both the deep muscle CSA of pre and post-operation, using SPSS ver. 15.0 program. Results : The results of this study showed a significant difference in deep muscle size (CSA) between pre and post operation (p<.05). Although there was not a meaningful difference between right and left deep muscle size (CSA) in pre operation (p>.05), there was a significant difference between both of them in post operation (p<.05). Conclusion : Therefore we made the conclusion that the operation causes decrease of muscle tone in deep muscles and muscle imbalance by causing muscle atrophy in the lumbar deep muscle after the operation.

Influence of Moving Mass on Dynamic Behavior of Simply Supported Timoshenko Beam with Crack

  • Yoon Han-Ik;Choi Chang-Soo;Son In-Soo
    • International Journal of Precision Engineering and Manufacturing
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    • v.7 no.1
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    • pp.24-29
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    • 2006
  • In this paper, the effect of open crack on the dynamic behavior of simply supported Timoshenko beam with a moving mass was studied. The influences of the depth and the position of the crack on the beam were studied on the dynamic behavior of the simply supported beam system by numerical methods. The equation of motion is derived by using Lagrange's equation. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments. The crack is modeled as a rotational spring. This flexibility matrix defines the relationship between the displacements and forces on the crack section and is derived by applying fundamental fracture mechanics theory. As the depth of the crack increases, the mid-span deflection of the Timoshenko beam with a moving mass is increased.

Vibration analysis of asymmetric shear wall and thin walled open section structures using transfer matrix method

  • Bozdogan, Kanat Burak;Ozturk, Duygu
    • Structural Engineering and Mechanics
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    • v.33 no.1
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    • pp.95-107
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    • 2009
  • A method for vibration analysis of asymmetric shear wall and Thin walled open section structures is presented in this paper. The whole structure is idealized as an equivalent bending-warping torsion beam in this method. The governing differential equations of equivalent bending-warping torsion beam are formulated using continuum approach and posed in the form of simple storey transfer matrix. By using the storey transfer matrices and point transfer matrices which consider the inertial forces, system transfer matrix is obtained. Natural frequencies can be calculated by applying the boundary conditions. The structural properties of building may change in the proposed method. A numerical example has been solved at the end of study by a program written in MATLAB to verify the presented method. The results of this example display the agreement between the proposed method and the other valid method given in literature.

Bending Analysis of Symmetrically Laminated Composite Open Section Beam Using the First-Order Shear Deformation Beam Theory (Timoshenko형 전단변형을 고려한 대칭적층 개단면 복합재 보의 휨해석)

  • 권효찬;박영석;신동구
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2000.04b
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    • pp.43-50
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    • 2000
  • In the first-order shear deformation laminated beam theory (FSDT), the Kirchhoff hypothesis is relaxed such that the transverse normals do not remain perpendicular to the midsurface after deformation. Bending behavior of laminated composite thin-walled beams with singly- and doubly-symmetric open sections under uniformly distributed and concentrated loads is analyzed by the Timoshenko-type thin-walled beam theory. A closed-form expression for the shear correction factor of I-shaped composite laminated section is obtained. Numerical examples are presented to compare present analytical solutions by FSDT with the finite element solutions obtained by using three dimensional model. The effects of lamination of scheme and length-to-height ratio on the shear deformation of laminated composite beams with various boundary conditions are studied.

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The Lecomte-Ueda Transformation and Resonance Structure in the Multichannel Quantum Defect Theory for the Two Open and One Closed Channel System

  • Lee, Chun-Woo;Kim, Ji-Hyun
    • Bulletin of the Korean Chemical Society
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    • v.23 no.11
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    • pp.1560-1567
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    • 2002
  • The transformation devised by Lecomte and Ueda for the study of resonance structures in the multichannel quantum defect theory (MQDT) is used to analyze partial photofragmentation cross section formulas in MQDT analogous to Fano's resonance formula obtained in the previous work for the system involving two open and one closed channels. Detailed comparison of the MQDT results with the configuration mixing (CM) ones is made. Resonance structures and their geometrical relations in the MQDT formulation are revealed and classified by combining Lecomte and Ueda's theory with the geometrical method devised to study the coupling between background and resonance scatterings.

A Study on Dimensional Change after Heat Treatment and Optimal Chemical Composition of Steels with 1200 MPa Tensile Strength for Automotive Subframe (인장강도 1200 MPa 급 자동차 서브 프레임의 합금성분 최적화 및 열변형 거동 연구)

  • Jeong, Woo Chang
    • Journal of the Korean Society for Heat Treatment
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    • v.33 no.3
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    • pp.107-116
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    • 2020
  • Four air hardening steels with carbon, silicon, manganese, chromium, and molybdenum variations have been used in this study to find out the optimal chemical compositions of steels with over 1200 MPa tensile strength for automotive subframe. The dimensional changes after heat treatment were determined for two automotive parts with open and closed cross sections using 3D scanner. When four steels were austenitized at 900℃ for 30 seconds, cooled at 3℃/s, reheated to 450℃ for 10 seconds followed by air cooling to simulate hot-dip galvanizing treatment showed ultra high tensile strength over 1200 MPa. Rear floor cross member with open cross section revealed much bigger dimensional changes than subframe with closed cross section after heat treatment at 900℃ for 20 minutes followed by air cooling.

A Study on the Dynamic Behavior of a Simply Supported Beam with Moving Masses and Cracks (이동질량과 크랙을 가진 단순지지 보의 동특성에 관한 연구)

  • 윤한익;손인수;조정래
    • Journal of Ocean Engineering and Technology
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    • v.17 no.6
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    • pp.47-52
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    • 2003
  • To determine the effect of transverse open crack on the dynamic behavior of simply-supported Euler-Bernoulli beam with the moving masses, an iterative modal analysis approach is developed. The influence of depth and position of the crack in the beam, on the dynamic behavior of the simply supported beam system, have been studied by numerical method. The cracked section is represented by a local flexibility matrix, connecting two undamaged beam segments that is, the crack is modeled as a rotational spring. This flexibility matrix defines the relationship between the displacements and forces across the crack section, and is derived by applying a fundamental fracture mechanics theory. As the depth of the crack is increased, the mid-span deflection of the simply-supported beam, with the moving mass, is increased. The crack is positioned in the middle point of the pipe, and the mid-span defection of the simply-supported pipe represents maximum deflection.

Dynamic Behavior of Timoshenko Beam with Crack and Moving Mass (크랙과 이동질량이 존재하는 티모센코 보의 동특성)

  • Yoon Han Ik;Choi Chang Soo;Son In Soo
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.1
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    • pp.143-151
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    • 2005
  • This paper study the effect of open cracks on the dynamic behavior of simply supported Timoshenko beam with a moving mass. The influences of the depth and the position of the crack in the beam have been studied on the dynamic behavior of the simply supported beam system by numerical method. Using Lagrange's equation derives the equation of motion. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments i.e. the crack is modeled as a rotational spring. This flexibility matrix defines the relationship between the displacements and forces on the crack section and is derived by the applying fundamental fracture mechanics theory. As the depth of the crack is increased the mid-span deflection of the Timoshenko beam with the moving mass is increased. And the effects of depth and position of crack on dynamic behavior of simply supported beam with moving mass are discussed.

Geometrically nonlinear analysis of thin-walled open-section composite beams

  • Vo, Thuc Phuong;Lee, Jae-Hong
    • Proceeding of KASS Symposium
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    • 2008.05a
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    • pp.113-118
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    • 2008
  • This paper presents a flexural-torsional analysis of thin-walled open-section composite beams. A general geometrically nonlinear model for thin-walled composite beams and general laminate stacking sequences is given by using systematic variational formulation based on the classical lamination theory. The nonlinear algebraic equations of present theory are linearized and solved by means of an incremental Newton-Raphson method. Based on the analytical model, a displacement-based one-dimensional finite element model is developed to formulate the problem. Numerical results are obtained for thin-walled composite beams under general loadings, addressing the effects of fiber angle, laminate stacking sequence and loading parameters.

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