• Title/Summary/Keyword: 양단자유

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A Study of Vibration Characteristics of Cylindrical Composite Shells Manufactured in Present Laboratory (간이 성형장치에 의해 제작된 복합재 원통셸의 진동특성평가)

  • 한병기;유택인;이성희;이재원
    • Composites Research
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    • v.12 no.1
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    • pp.37-46
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    • 1999
  • In this study, the vibration analysis and modal tests of cylindrical composite shells which are manufactured with various stacking sequences in present laboratory were conducted under the free-free and clamped-clamped boundary conditions. Natural frequencies and mode shapes of these specimens were experimentally obtained and their results are compared with theoretical and FEM results. Both results are in good agreement, which confirm the usefulness of proposed manufacturing method for cylindrical composite shells.

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The Study of the Characteristics of Radiation Efficiency from the Point-Excited Cylindrical Shell under the Free Ends (점-조화 가진에 의한 양단 자유지지 경계 조건을 갖는 원통 셸의 방사 효율 특성에 관한 연구)

  • 김관주
    • Proceedings of the Acoustical Society of Korea Conference
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    • 1998.06e
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    • pp.103-106
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    • 1998
  • 본 논문은 상용 FEM-BEM 프로그램을 사용하여 점-조화 가진(harmonic point excitation)에 의한 자유지지 경계 조건을 갖는 원통 셸(cylindrical shell)의 방사 효율(radiation efficiency) 실험의 결과와 비교하였다. 우선 충격 해머 실험(impact hammer test)을 통한 모드 시험(modal testing)으로 원통 셸의 공진 주파수(natural frequency)와 모드 형상(mode shape)의 특징을 살펴보고 다음으로 점-조화 가진에 의한 원통 셸의 방사 효율을 SYSNOISE와 ANSYS로 해석해 보았다. 동시에 음향 세기 실험을 통한 방사 효율을 측정하여 전산 해석의 결과와 실험의 결과를 비교해 보았다.

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A Simple Method of Vibration Analysis of Speical Orthotropic Plate with A Pair of Opposite Edges Simply Supported and the Other Pair of Opposite Edges Free (양단단순-타단자유인 특별직교이방성 적층복합판의 간편한 진동해석)

  • 김덕현;이정호;홍창우;박제선
    • Composites Research
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    • v.12 no.4
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    • pp.33-41
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    • 1999
  • In this paper, a simple but accurate method of vibration analysis of structural elements with or without attached mass/masses is presented. The method used has been developed by D.H., Kim since 1974. This method is very effective for the plates with arbitrary conditions and irregular sections. This method is applied to the special orthotropic plate with two opposite edges simply supported and the other two opposite edges free. Such plate represents the most of the simply supported bridges/decks, including concrete and girders-cross beam systems. Detailed illustration is given for beams and plates for easy understanding. Some laminate orientation for which the special orthotropic equations can be applied are identified.

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Free Vibrations of Clamped Circular Arches with Linear Variable Cross-Section (1차원 변화단면을 갖는 양단고정 원호아치의 자유진동 해석)

  • Lee, Byoung Koo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.9 no.4
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    • pp.1-8
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    • 1989
  • The main purpose of the present paper is to present both the fundamental frequency and some higher free vibration frequencies for circular arches with variable section, in which rotatory inertia is included. The differential equations are derived for the in-plan free vibration of elastic circular arches with variable section. These equations were solved numerically for the linear variable circular cross-section with clamped-clamped end constraint. As the numerical results, the four lowest nondimensional natural frequencies presented as functions of the nondimensional system parameters : the end moment of inertia to crown moment of inertia ratio, the slenderness ratio, and the opening angle. The effect of rotatory inertia on the nondimensional natural frequency is also reported.

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Determination of Dynamic Free Span Length for Subsea Pipelines with General Boundary Conditions (일반화된 경계조건을 갖는 해저파이프라인의 동적 자유경간 결정 방법)

  • 박한일
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.13 no.4
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    • pp.290-295
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    • 2001
  • Subsets pipelines are exposed to several potential risks of damage due to corrosion, soil instability, anchor impact and other hazards. One of the main risk factors for the safety of a subsea pipeline is its free spanning. This paper examines the safety of subsea pipelines with free span under axial compressive load. The variation of allowable lengths of dynamic free span is examined for generalized boundary conditions. The free span is modelled as a beam with an elastic foundations and the boundary condition is replaced by linear and rotational springs at each end. A dynamic free span curve is obtained with a function of non-dimensional parameters and can be used usefully for the design of subsea pipelines with a free span. A case study is carried out to introduce the application method of the curve.

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Static and Dynamic Optimal Shapes of Both Clamped Columns with Constant Volume (일정체적 양단고정 기둥의 정·동적 최적형상)

  • Lee, Byoung Koo;Kim, Suk Ki
    • Journal of Korean Society of Steel Construction
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    • v.19 no.1
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    • pp.99-106
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    • 2007
  • This paper deals with the static and dynamic optimal shapes of both clamped columns with constant volume. The parabolic taper with the regular polygon cross-section is considered, whose material volume and column length are held constant. Numerical methods are developed for solving natural frequencies and buckling loads of columns subjected to an axial compressive load. Differential equations governing the free vibrations of such column are derived. The Runge-Kutta method is used to integrate the differential equations, and the Regula-Falsi method is used to determine natural frequencies and buckling loads, respectively. From the numerical results, dynamic stability regions, dynamic optimal shapes and configurations of strongest columns are presented in figures and tables.

Free Vibration of Orthotropic Laminated Composite Conical Shells (직교이방성 적층 복합재료 원추셸의 자유진동)

  • 이영신;강인식
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.13 no.4
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    • pp.595-603
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    • 1989
  • Free vibration of orthotropic laminated composite conical shells with constant thickness are considered. Governing frequency equations are derived based on the Flugge theory and Galerkin method is applied for the numerical analysis. Comparisons are made between present results and others for the isotropic conical shells and numerical results are obtained based on these results for the specially orthotropic laminated composite conical shells with simply supported edges. Variations of frequency parameter on the change of material properties, stacking sequences, stacking number, geometrical parameters and orthotropic parameters are considered in the analysis.

A Simple Method of Vibration Analysis of Special Orthotropic Plate with A Pair of Opposite Edges Simply Supported and The Other Pair of Opposite Edges Free (양단단순-양단자유지지된 특별직교 이방성 적층복합판의 진동해석을 위한 간편법)

  • Kim Duk-Hyun;Kim, Kyeong-Jin;Hong, Chang-Woo
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1996.04a
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    • pp.135-142
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    • 1996
  • In this paper, a simple tut accurate method of vibration analysis of structural elements with or without attached mass/masses is presented. The method used has been developed by the senior author since 1974. This method is very effective for the plates with arbitrary boundary conditions and irregular sections. This method is applied to the special orthotropic Plate with two opposite edges simply supported and the other two opposite edges free. Such plate represents the most of the simply supported bridges/decks, including concrete and girders-cross beam systems. Detailed illustration is given for beams and plates for easy understanding. Some laminate orientation for which the special orthotropic equations can be applied are identified.

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Free Vibrations and Buckling Loads of Beam-Columns on Winkler-Type Foundations (Winkler형 지반위에 놓인 보-기둥의 자유진동 및 좌굴하중 해석)

  • Jeong, Jin Seob;Lee, Byoung Koo;Oh, Sang Jin
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.13 no.4
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    • pp.251-258
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    • 1993
  • The main purpose of this paper is to present both the natural frequencies and the buckling loads of beam-columns on Winkler-type foundations. The ordinary differential equations governing the free vibrations and the buckling loads of beam-columns on Winkler-type foundation are derived as nondimensional forms. The Runge-Kutta method and Determinant Search method are used to perform the integration of the differential equations and to determine the eigenvalues(natural frequencies and buckling loads), respectively. Hinged-hinged and damped-clamped end constraints are applied in numerical examples. The relation between frequency parameter and elastic foundation parameter is presented in figure. The effects of axial loads on the natural frequencies of beam-columns on elastic foundations are investigated and the relation between buckling load parameter and elastic foundation parameter is also analyzed. The relation between foundation rested ratio and frequency parameter, buckling load parameter are investigated. The beam-columns on non-homogeneous elastic foundation are analyzed and typical mode shapes are also presented.

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