• 제목/요약/키워드: Stiffened-plate

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보강재의 운동으로 인한 보강판의 연성진동 (Coupled Vibration of Stiffened Plates due to Motion of Stiffeners)

  • 이현엽
    • 소음진동
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    • 제7권1호
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    • pp.153-159
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    • 1997
  • In a stiffened plate reinforced on one of its sides by beam type stiffeners, the asymmetry about the plate mid-plane induces coupling between flexural wave and longitudinal wave. In this research interactions between flexural and longitudinal wave motion are analyzed in a stiffened plate which is reinforced only in one direction. The plate is modelled as a beam to which offset spring-mounted masses are attached at regular intervals. Propagation constants of the coupled waves and corresponding characteristic waves are derived by using periodic structure theory, and a computer code is developed. Also, sample calculations are carried out and the results are discussed.

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보강재의 수를 포함한 보강판 구조물의 동특성의 최적변경 (The Optimum Modification of Dynamic Characteristics of Stiffened Plate Structure Including the Number of Stiffener)

  • 박성현;고재용
    • 한국항해학회지
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    • 제25권4호
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    • pp.461-469
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    • 2001
  • The purpose of this paper is the optimum modification of dynamic characteristics of stiffened plate structure including the number of stiffener. This paper shows the optimum structural modification method by dynamic sensitivity analysis and quasi-least squares method and considers it's validity. In the method of the optimization, finite element method, sensitivity analysis and optimum structural modification method are used. The change of natural frequency and total weight are made to be an objective function. Thickness of plate, the number of stiffener and cross section moment of stiffener become a design variable. The dynamic characteristics of stiffened plate structure is analyzed using finite element method. Next, rate of change of dynamic characteristics by the change of design variable is calculated using the sensitivity analysis. Then, amount of change of design variable is calculated using optimum structural modification method. It is shown that the results are effective in the optimum modification for dynamic characteristics of the stiffened plate structure including the number of stiffener.

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보강판 제원에 따른 개단면 리브 보강판의 국부 처짐과 국부 모멘트의 정형화 (Formulating the Local Displacement and Local Moments of a Plate Stiffened with Open Ribs According to the Dimensions of Stiffened Plates)

  • 주석범
    • 한국강구조학회 논문집
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    • 제24권6호
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    • pp.659-670
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    • 2012
  • 본 연구에서는 개단면 리브 보강판에 대하여 여러 가지 제원 변화에 따른 국부 처짐과 국부 모멘트를 정형화하고자 하였다. 평강 리브와 역T형 리브를 갖는 여러 가지 보강판을 분석한 결과, 하부 플랜지가 국부 거동에 미치는 영향이 매우 작아 국부 거동은 리브 간격, 복부 두께와 높이, 판 두께에 대한 비율 함수로 표현할 수 있음을 알 수 있었다. 또한, 평강 리브와 역T형 리브를 갖는 보강판의 비율 함수가 유사한 결과를 나타내어 하나의 비율 함수로 통합 가능하였으며, 이를 적용한 결과 타당한 결과를 나타내었다. 다른 형태의 보강판에 비율 함수를 적용한 결과, 오차율 증가가 크지 않아 본 연구의 적용성을 확인할 수 있었다. 따라서 본 연구에서 제안한 국부 거동에 대한 비율 함수식을 이용하면, 개단면 리브를 갖는 보강판의 국부 처짐과 국부 모멘트에 대하여 제원과 상관없이 간편하게 타당한 결과를 얻을 수 있을 것으로 판단된다.

고유진동수의 간이 추정식을 이용한 보강판 구조물의 동특성의 최적변경에 관한 연구 (A Study on Optimum Modification of Dynamic Characteristics of Stiffened Plate Using Simplified Equation of Natural Frequency)

  • 박성현;남정길
    • Journal of Advanced Marine Engineering and Technology
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    • 제26권1호
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    • pp.48-58
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    • 2002
  • There is a purpose of this study for the proposal of the optimum technique utilized for the vibration design initial step. The stiffened plate structure for the ship hull is made for analysis model. To begin with, dynamic characteristics of stiffened plate structure is analysed using FEM. Main vibrational mode of the structure is decided in the analytical result of FEM. The simplified equation on the natural frequency of the main vibrational mode is induced. Next, sensitivity analysis is carried out using the simplified equation, and rate of change of dynamic characteristics is calculated. Then, amount of design variable is calculated using this sensitivity value and optimum structural modification method. The change of natural frequency is made to be an objective function. Thickness of panel, cross section moment of stiffener and girder become a design variable. The validity of the optimization method using simplified equation is examined. It is shown that the result effective in the optimum modification for natural frequency of the stiffened plate structure.

탄성지지부가물(彈性支持附加物) 또는 집중질량(集中質量)을 갖는 보강판(補剛板)의 진동해석(振動解析) (Vibration Analysis of Stiffened Plates having a Resiliently Mounted or Concentrated Mass)

  • 한성용;김극천
    • 대한조선학회지
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    • 제23권1호
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    • pp.23-32
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    • 1986
  • By virtue of an application of the receptance method, simplified formulae to calculate natural frequencies of stiffened plates having a resiliently mounted or concentrated mass are obtained. Some numerical results are compared with those based on Lagrange's equation of motion and with experimental results. For the problem formulation the stiffened plate is reduced to an equivalent orthotropic plate, a resiliently mounted mass to a spring-mass system, and mode shapes of the plate are assumed with comparison functions consisting of Euler beam functions. The proposed formulae give results in good conformity to both numerical results based on Lagrange's equation of motion and experimental results for in-phase modes of the coupled system. For out-of-phase modes the conformity is assured only in case that the natural frequency of the attached system is less than a half of that the stiffened plate. It is also found that a resiliently mounted mass having its own natural frequency of about two or more times that of the stiffened plate can be reduced to a concentrated mass with assurance of a few percent error in the frequency.

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보강판의 방사소음저감을 위한 제진재의 최적 위치 선정 (Optimal Adherent Position of Viscoelastic Material for the Reduction of Sound Power Radiated from the Stiffened Plate)

  • 김사수;조대승;안호일;정상민
    • 한국해양공학회지
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    • 제12권2호통권28호
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    • pp.22-32
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    • 1998
  • Many of steel structures having little internal damping consist of stiffened plates. In case that viscoelastic materials are adhered to the stiffened plates for the reduction of structure-borne noise, their effects are varied by the adhered position and dynamic characteristics of the structures as well as their material properties and adhered amount. In this paper, sound reduction effects of viscoelastic materials partially adhered to the different positions of a stiffened steel plate have been investigated by the measurement of vibratory velocity and sound intensity. The results show that optimal adherent positions of viscoelastic materials to reduce sound radiation power are the loop areas of modes.

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Numerical procedure for the vibration analysis of arbitrarily constrained stiffened panels with openings

  • Cho, Dae Seung;Vladimir, Nikola;Choi, Tae Muk
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제6권4호
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    • pp.763-774
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    • 2014
  • A simple and efficient vibration analysis procedure for stiffened panels with openings and arbitrary boundary conditions based on the assumed mode method is presented. Natural frequencies and modes are determined by solving an eigenvalue problem of a multi-degree-of-freedom system matrix equation derived by using Lagrange's equations of motion, where Mindlin theory is applied for plate and Timoshenko beam theory for stiffeners. The effect of stiffeners on vibration response is taken into account by adding their strain and kinetic energies to the corresponding plate energies whereas the strain and kinetic energies of openings are subtracted from the plate energies. Different stiffened panels with various opening shapes and dispositions for several combinations of boundary conditions are analyzed and the results show good agreement with those obtained by the finite element analysis. Hence, the proposed procedure is especially appropriate for use in the preliminary design stage of stiffened panels with openings.

보강판(補剛板)의 좌굴해석(挫屈解析) (Buckling Analysis of Stiffened Plates)

  • 임상전;양박달치
    • 대한조선학회지
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    • 제18권2호
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    • pp.1-6
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    • 1981
  • The buckling of stiffened plates is considered using a finite element method. In this paper stiffened plates are treated as orthotropic plates and by appling Mindlin's plate theory the effects of shear deformation to buckling loads are considered. In general, it is found that for moderately thick plates Mindlin's plate theory gives lower buckling load than those obtained using classical thin plate theory.

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Dynamic behaviour of multi-stiffened plates

  • Bedair, Osama
    • Structural Engineering and Mechanics
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    • 제31권3호
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    • pp.277-296
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    • 2009
  • The paper investigates the dynamic behaviour of stiffened panels. The coupled differential equations for eccentric stiffening configuration are first derived. Then a semi-analytical procedure for dynamic analysis of stiffened panels is presented. Unlike finite element or finite strip methods, where the plate is discretized into a set of elements or strips, the plate in this procedure is treated as a single element. The potential energy of the structure is first expressed in terms generalized functions that describe the longitudinal and transverse displacement profiles. The resulting non-linear strain energy functions are then transformed into unconstrained optimization problem in which mathematical programming techniques are employed to determine the magnitude of the lowest natural frequency and the associated mode shape for pre-selected plate/stiffener geometric parameters. The described procedure is verified with other numerical methods for several stiffened panels. Results are then presented showing the variation of the natural frequency with plate/stiffener geometric parameters for various stiffening configurations.

Timoshenko 보함수 성질을 갖는 다항식을 이용한 보강판의 교유진동 해석 (Free Vibration Analysis of Stiffened Plates Using Polynomials Having the Property of Timoshenko Beam Functions)

  • 김병희;김진형;조대승
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2004년도 춘계학술대회논문집
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    • pp.623-628
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    • 2004
  • In this study, the assumed-mode method using characteristic polynomials of Timoshenko beam is applied for the free vibration analysis of rectangular stiffened plates. The polynomial is derived considering the rotational constraint along the boundary edges of plate and the orthogonal relation of Timoshenko beam functions, which enables to simplify the free vibration analysis of plate structure having various boundary conditions. To verify the validity and effectiveness of the adopted method, numerical analysis for cross-stiffened plates were carried out and its results were compared with those obtained by the general purpose FEA software.

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