• 제목/요약/키워드: variable curvature

검색결과 108건 처리시간 0.023초

불연속 변화단면 변화곡률 수평 곡선보의 자유진동 (Free Vibrations of Stepped Horizontally Curved Beams with Variable Curvature)

  • 이태은;안대순;이병구;김권식
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2003년도 춘계학술대회논문집
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    • pp.858-863
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    • 2003
  • In the practical engineering fields, the horizontally curved beams are frequently erected as the major/minor structural components. The effects of both variable curvature and variable cross-section on structural behavior are very important and therefore these effects should be included in structural analyses. From this viewpoint, this paper deals with the free vibrations of horizontally curved beams with variable curvature and variable cross-section. In this study, the parabola as the curvilinear shape and stepped beam as the variable cross-section are considered. The ordinary differential equation governing free vibrations of such beams are derived. For calculating the natural frequencies, the governing equations are solved by numerical methods. The Runge-Kutta and Determinant search Methods are used for integrating the differential equations and for calculating the natural frequencies, respectively. With regard to numerical results, the relationships between frequency parameters and various beam parameters are presented in the forms of Table and Figures.

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변단면 변화곡율 캔틸레버 아치의 자유진동 (Free Vibrations of Tapered Cantilever Arches with Variable Curvature)

  • 이병구;이용수;오상진
    • 소음진동
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    • 제10권2호
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    • pp.353-360
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    • 2000
  • Numerical methods are developed for calculating the natural frequencies and mode shapes of the tapered cantilever arches with variable curvature. The differential equations governing the free vibrations of such arches are derived and solved numerically, in which the effect of rotatory inertia is included. The parabolic shape is chosen as the arch with variable curvature while both the prime and quadratic arched members are considered as the tapered arch with variable curvature while both the prime and quadratic arched members are considered as the tapered arch. Comparisons the natural jfrequencies between this study and finite element method SAP 90 seve to validate the numerical method developed herein. The lowest four natural frequencies are reported as a function of four non-dimensional system parameters. The effects of both the rotatory inertia and cross-sectional shape are reported. Also, the typical mode shapes of stress resultants as well as the displacements are reported.

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자동차 알루미늄 범퍼의 가변 곡률 압출공정 개발 (Process Development of Variable Curvature Extrusion for Automotive Aluminum Bumper)

  • 조영준;이상곤;오개희;박상우;김병민
    • 대한기계학회논문집A
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    • 제32권4호
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    • pp.327-332
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    • 2008
  • The effectiveness of vehicle parts made through extrusion is in the limelight because of the advantages of high strength stiffness materials can be produced and the number of processes can be drastically reduced. Therefore, the parts should have sufficient stiffness and be lightweight enough to improve fuel efficiency. However, the application of extruded aluminum requires pre-bending technologies that can manufacture the complex designs profiles demanded by vehicle parts. The aim of this research is that the development of the variable curvature extrusion technology that can produce a variety of curvature. In order to produce a variable curvature, the guide transfer speed and transfer time should be controlled properly. The guide transfer speed and transfer time were examined by the theoretical analysis. A model was developed to simulate the deformation behaviors of extrusion and bending process from the symmetric bumper with range of radii from 1863mm to 2163mm. The theoretical analysis and FE analysis were verified through experimental method.

NON-ZERO CONSTANT CURVATURE FACTORABLE SURFACES IN PSEUDO-GALILEAN SPACE

  • Aydin, Muhittin Evren;Kulahci, Mihriban;Ogrenmis, Alper Osman
    • 대한수학회논문집
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    • 제33권1호
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    • pp.247-259
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    • 2018
  • Factorable surfaces, i.e. graphs associated with the product of two functions of one variable, constitute a wide class of surfaces in differential geometry. Such surfaces in the pseudo-Galilean space with zero Gaussian and mean curvature were obtained in [2]. In this study, we provide new results relating to the factorable surfaces with non-zero constant Gaussian and mean curvature.

임의의 곡률과 변두께를 갖는 두꺼운 축대칭 회전 셸의 3차원적 장방정식, 운동 방정식, 에너지 범함수 (Three-Dimensional Field Equations, Equations of Motion, and Energy Functionals for Thick Shells of Revolution with Arbitrary Curvature and Variable Thickness)

  • 강재훈;이은택;양근혁
    • 소음진동
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    • 제11권1호
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    • pp.156-166
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    • 2001
  • This work uses tensor calculus to derive a complete set of three-dimensional field equations well-suited for determining the behavior of thick shells of revolution having arbitrary curvature and variable thickness. The material is assumed to be homogeneous, isotropic and linearly elastic. The equations are expressed in terms of coordinates tangent and normal to the shell middle surface. The relationships are combined to yield equations of motion in terms of orthogonal displacement components taken in the meridional, normal and circumferential directions. Strain energy and kinetic energy functionals are also presented. The equations of motion and energy functionals may be used to determine the static or dynamic displacements and stresses in shells of revolution, including free and forced vibration and wave propagation.

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Exact solution for free vibration of curved beams with variable curvature and torsion

  • Zhu, Li-Li;Zhao, Ying-Hua;Wang, Guang-Xin
    • Structural Engineering and Mechanics
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    • 제47권3호
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    • pp.345-359
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    • 2013
  • For the purpose of investigating the free vibration response of the spatial curved beams, the governing equations are derived in matrix formats, considering the variable curvature and torsion. The theory includes all the effects of rotary inertia, shear and axial deformations. Frobenius' scheme and the dynamic stiffness method are then applied to solve these equations. A computer program is coded in Mathematica according to the proposed method. As a special case, the dynamic stiffness and further the natural frequencies of a cylindrical helical spring under fixed-fixed boundary condition are carried out. Comparison of the present results with the FEM results using body elements in I-DEAS shows good accuracy in computation and validity of the model. Further, the present model is used for reciprocal spiral rods with different boundary conditions, and the comparison with FEM results shows that only a limited number of terms in the resultant provide a relatively accurate solution.

Sensitivity analysis of variable curvature friction pendulum isolator under near-fault ground motions

  • Shahbazi, Parisa;Taghikhany, Touraj
    • Smart Structures and Systems
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    • 제20권1호
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    • pp.23-33
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    • 2017
  • Variable Curvature Friction Pendulum (VCFP) bearing is one of the alternatives to control excessive induced responses of isolated structures subjected to near-fault ground motions. The curvature of sliding surface in this isolator is varying with displacement and its function is non-spherical. Selecting the most appropriate function for the sliding surface depends on the design objectives and ground motion characteristics. To date, few polynomial functions have been experimentally tested for VCFP however it needs comprehensive parametric study to find out which one provides the most effective behavior. Herein, seismic performance of the isolated structure mounted on VCFP is investigated with two different polynomial functions of the sliding surface (Order 4 and 6). By variation of the constants in these functions through changing design parameters, 120 cases of isolators are evaluated and the most proper function is explored to minimize floor acceleration and/or isolator displacement under different hazard levels. Beside representing the desire sliding surface with adaptive behavior, it was shown that the polynomial function with order 6 has least possible floor acceleration under seven near-field ground motions in different levels.

곡률 변화형 테이피를 이용한 도파관-마이크로스트립 트랜지션 (A Waveguide-Microstrip Transition using Curvature Variable Taper)

  • 차원석;조영송;신철재
    • 전자공학회논문지A
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    • 제31A권2호
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    • pp.45-52
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    • 1994
  • A curvature variable taper is proposed for a waveguide-microstrip transition. It is applied to a ridge waveguide. The curvature depends on the taper length and difference of waveguide's height and microstrip substrate's height. The taper is manufactured easier than the other tapers. It's reflection coefficient is smaller than the parabolic taper's below one wavelengrh. The results of experiment show that S$_{11}$ is below -20dB and SS$_{21}$ is about -0.5dB in the band of 10~15 GHz. These results are good agreement with the theoritical values.

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회전관성 및 전단변형이 변화곡률 아치의 고유진동수에 미치는 영향 (Effects of Rotatory Inertia and Shear Deformation on Natural Frequencies of Arches with Variable Curvature)

  • 오상진;이병구;이인원
    • 한국강구조학회 논문집
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    • 제9권4호통권33호
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    • pp.673-682
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    • 1997
  • 이 논문에서는 회전관성과 전단변형이 변화곡률 아치의 고유진동수에 미치는 영향을 분석하였다. 임의의 변화곡률을 갖는 등단면 아치의 자유진동을 지배하는 미분방정식을 유도하였으며, 유도된 미분방정식에 회전-회전, 회전-고정 및 고정-고정의 단부조건을 갖는 포물선, 원호 및 타원 아치를 적용하여 수치해석하였다. 해석결과로서 무차원 변수인 아치높이 지간길이비 및 세장비 변화에 따론 최저차 4개의 무차원 고유진동수를 산출하였다.

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