• 제목/요약/키워드: Circular Vibration

검색결과 516건 처리시간 0.025초

Eigenvalue analysis of axisymmetric circular Mindlin plates by pseudospectral method

  • Lee, Jinhee
    • International Journal of Precision Engineering and Manufacturing
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    • 제3권3호
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    • pp.44-49
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    • 2002
  • A study of free vibration of axisymmetric circular plates based on Mindlin theory using a pseudospectral method is presented. The analysis is based on Chebyshev polynomials that are widely used in the fluid mechanics research community. Clamped, simply supported and flee boundary conditions are considered, and numerical results are presented for various thickness-to-radius ratios.

Free vibrations of circular arches with variable cross-section

  • Wilson, James F.;Lee, Byoung Koo;Oh, Sang Jin
    • Structural Engineering and Mechanics
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    • 제2권4호
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    • pp.345-357
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    • 1994
  • The differential equations governing free, in-plane vibrations of linearly elastic circular arches with variable cross-sections are derived and solve numerically for quadratic arches with three types of rectangular cross sections. Frequencies, mode shapes, cross-sectional load distributions, and the effects of rotatory inertia on frequencies are reported. Experimental measurements of frequencies and their corresponding mode shapes agree closely with those predicted by theory. The numerical methods presented here for computing frequencies and mode shapes are efficient and reliable.

다단 티모센코 원형단면봉의 연속 고유모우드 (Mode Shape of Timoshenko Beam Having Different Circular Cross-Sections)

  • 전오성
    • 한국생산제조학회지
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    • 제6권4호
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    • pp.118-123
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    • 1997
  • The study suggests a method to analyze the vibration of the multi-stepped beam having the different circular cross-sections. The rotatory inertia, the shear deformation and the torque applied at both ends of the beam are considered in the governing equation. The complex displacement and the variable separation are introduced to derive the solution of the equation of each uniform beam element having constant cross-section. Then boundary conditions are applied to solve the total system. This method uses the mathematically exact solutions unlike numerical method such as the finite element method in solving the problem having the simultaneous differential equations of Timoshenko beam theory. the natural frequencies and the corresponding mode shapes are precise, especially the mode shapes are continuous.

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원형 고무 세그먼트를 갖는 탄성 커플링의 동특성과 적응성 (Dynamic Characteristics and Adaptation of Elastic Coupling with Rubber Type Circular Segments)

  • 이돈출;김진경;남택근;유정대
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2008년도 춘계학술대회논문집
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    • pp.90-95
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    • 2008
  • Medium and high speed marine diesel engines have been widely used as prime mover in small car ferries and fishing vessels with reduction gear. These propulsion shafting system should be installed and matched the elastic coupling between engine and reduction gear to isolate the vibratory torque. In this paper, the elastic dynamic characteristics of coupling with rubber type circular segments is confirmed by the theoretical analysis using the FEM and the hydraulic exciting test at shop. And its adaptation is investigated in the torsional vibration test in factory shop.

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스퍼 기어계의 방사소음 예측 (Prediction of Radiated Noise from a Spur Gear System)

  • 박찬일
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2000년도 춘계학술대회논문집
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    • pp.334-339
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    • 2000
  • In order to predict the noise of the spur gear system, a simplified model of spur system including the housing is studied. The spur gear is modeled as a single degree of freedom system. The shaft-housing system is modeled as a clamped circular plate connected with a beam. The moment components of the beam excited by the spur gear mesh force are considered in the calculation of plate vibration and radiated noise. The out-of-displacements of the clamped circular plate due to the r-direction moment and ${\theta}$-direction moment are calculated. Radiated noise from the plate in the air is also calculated using Rayleigh integral. Using the numerical example, the numerical validation of the analytical procedure on the noise prediction are given.

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원형 고무 세그먼트를 갖는 탄성커플링의 동특성과 적응성 (Dynamic Characteristics and Adaptation of Elastic Coupling with Rubber Type Circular Segments)

  • 이돈출;로날드 디. 바로;김진경;남택근;유정대
    • 한국소음진동공학회논문집
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    • 제21권4호
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    • pp.346-351
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    • 2011
  • Medium and high speed marine diesel engines with reduction gear have been widely used as prime mover in small car ferries and fishing vessels. The elastic coupling should be installed and complemented the propulsion shafting system to isolate the vibratory torque between engine and reduction gear. In this paper, the dynamic characteristics of elastic coupling with rubber type circular segments is confirmed by theoretical analysis using the FEM and the hydraulic excitation test at shop. Further adaptation was investigated with the torsional vibration test at diesel engine factory shop.

넓은 환상간극을 가진 동심원통속의 couette 흐름에서 고분자수용액의 유동현상 (A flow phenomenon of aquaous polymer solution in couette flow of concentric cylinder with wide circular)

  • 권혁칠;이성노;정진도
    • 오토저널
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    • 제15권3호
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    • pp.81-88
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    • 1993
  • This report describes the experimental research on the flow phenomena of the aq uaous polymer solution within the Cuette flow of the concentric, cylinders type with a wide circular gap. We have investigated the phenomena of the fluid flow through torque measuring in the system that the inner cylinder is stationary and the outer one is rotating. Geometrical parameters of the system are the gap ratio of t/R$_{0}$=0.2 and Aspect ratio of l/t=100. The torque increases considerably in about 420-480RPM, So, it is considered a turbulent transition boundary, the higher plymer concentration is, the lower torque value is and the higher transition Reynolds number is. In each of the polymer concentration, the unstable boundary of torque, that is, idiosyncrasies of torque is observed around 220-280RPM. and the boundary is looked upon as a resonant vibration which is caused by the inner cylinder and tortional vibration of torque sensor.r.

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비대칭 단면을 갖는 박벽 곡선보의 자유진동 해석 (Free Vibration Analysis of Thin-walled Curved Beams with Unsymmetric Cross-section)

  • 김문영
    • 한국지진공학회논문집
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    • 제3권1호
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    • pp.41-54
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    • 1999
  • 비대칭 박벽단면을 갖는 곡선보의 자유진동해석을 수행할 수 있는 유한요소 이론 및 엄밀해를 제시하기 위하여 가상일의 원리를 이용한 3차원 연속체의 운동방정식을 제시한다 박벽단면의 구속된 비틂효과를 고려하는 박벽 곡선보의 변위장을 도입하고 이를 연소체의 운동방정식에 대입하여 단면에 대해 적분함으로써 박벽 곡선보의 운동방정식을 유도한다. 단순지지되고 일축대칭단면을 갖는 박벽 곡선보의 면내 자유진동 모드에 대응하는엄밀해를 산정하였으며 곡선보를 유한요소로 분할하여 요소의 변위장을 요소 변위벡터에 관한 3차의 Hermitian 다항식으로 나타내고 이를 운동방정식에 대입함으로써 탄성강도행렬과 질량 행렬을 유도한다 또한 본 연구에서 얻어진 엄밀해와 곡선보요소를 이용한 유한요소 해석결과를 직선보요소 및 ABAQUS의 쉘요소를 이용하여 얻어진 결과와 비교 검토를 함으로써 본 연구의 타당성을 입증한다.

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기하학적 비선형성을 고려한 유체를 수송하는 반원관의 면내운동에 대한 진동 해석 (Vibration Analysis for the In-plane Motions of a Semi-Circular Pipe Conveying Fluid Considering the Geometric Nonlinearity)

  • 정진태;정두한
    • 대한기계학회논문집A
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    • 제28권12호
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    • pp.2012-2018
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    • 2004
  • The vibration of a semi-circular pipe conveying fluid is studied when the pipe is clamped at both ends. To consider the geometric nonlinearity, this study adopts the Lagrange strain theory for large deformation and the extensible dynamics based on the Euler-Bernoulli beam theory for slenderness assumption. By using the Hamilton principle, the non-linear partial differential equations are derived for the in-plane motions of the pipe, considering the fluid inertia forces as a kind of non-conservative forces. The linear and non-linear terms in the governing equations are compared with those in the previous study, and some significant differences are discussed. To investigate the dynamic characteristics of the system, the discretized equations of motion are derived from the Galerkin method. The natural frequencies varying with the flow velocity are computed from the two cases, which one is the linear problem and the other is the linearized problem in the neighborhood of the equilibrium position. Finally, the time responses at various flow velocities are directly computed by using the generalized-$\alpha$ method. From these results, we should consider the geometric nonlinearity to analyze dynamics of a semi-circular pipe conveying fluid more precisely.

횡유동장에 놓인 원형 실린더 군 주위의 유동장 해석 (An Analysis on Cross Flows around a Group of Circular Cylinders)

  • 심우건;김태한
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 춘계학술대회논문집E
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    • pp.582-587
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    • 2001
  • A numerical method using FLUENT code was employed to investigate fluid drag and lift forces on a cylinder in a group of circular cylinders, subjected to a uniform cross flow. The cylinders can be arranged in tandem or in a staggered arrangements relative to the free stream flow. A vortex street behind the cylinder pairs or jets between the cylinders forms according to the arrangements. Vibration on a cylinder can occurs due to vortex shedding, fluid-elastic stiffness and wake galloping. The flow is first investigated and then the forces acting on the cylinder are calculated. The lift and drag forces on an elastically mounted cylinder in the wake of an upstream fixed cylinder arise from the mean flow plus velocity and pressure gradients in the wake. The analytical results of two staggered cylinder were compared with the existing experimental ones for validation of the present method. The analytical results of the forces were in good agreement with the experimental ones. The present method can be used for the analysis of the fluid induced vibration where the group of circular cylinders are subjected to a cross flow.

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