• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.1181-1184
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• 2007

이 논문에서는 단부가 힌지와 회전스프링으로 지지된 원호 아치의 면내 자유진동에 대한 지배 미분방정식을 수치해석하여 대상 구조에 대한 최저차 4개의 고유진동수 및 진동형을 산출하였다. 축변형, 회전관성 및 전단변형 효과를 고려한 지배방정식을 채택하였으며, 해석결과로서 아치 중심각, 세장비 및 단부의 회전스프링상수 변화에 따른 고유진동수 및 진동형의 변화를 고찰하였다.

• Structural Engineering and Mechanics
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• 제64권1호
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• pp.1-10
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• 2017

The present paper deals with the free vibration and buckling problem with consideration of surface properties of circular nanobeams and nanoarches. The Gurtin-Murdach theory is used for investigating the surface effects parameters including surface tension, surface density and surface elasticity. Both linear and nonlinear elastic foundation effect are considered on the circular curved nanobeam. The analytically Navier solution is employed to solve the governing equations. It is obviously detected that the natural frequencies of a curved nanobeams is substantially influenced by the elastic foundations. Besides, it is revealed that by increasing the thickness of curved nanobeam, the influence of surface properties and elastic foundations reduce to vanished, and the natural frequency and critical buckling load turns into to the corresponding classical values.

• 소음진동
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• 제8권5호
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• pp.908-913
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• 1998

Analogous problem for a gear dynamics where helical gears excite logitudinal forces in the shaft is studied. These shaft forces excite the supporting gear housing through bearing, causing structural vibration. In this study, shaft is modeled as a rod, and bearing is modeled by a massless spring. A simple model for gear housing is a clamped circular plate. To model this force transmission, the transfer functions from the shaft to a clamped circular plate are analytically derived by using the spectral method and four-pole parameter. Finally, radiated noise is computed, using the acoustic relations due to plate surface vibration.

• 한국소음진동공학회논문집
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• 제20권2호
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• pp.144-152
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• 2010

This paper deals with free vibrations of the tapered circular arches with constant volume, whose cross sectional shape is the solid regular polygon. Volumes of the objective arches are always held constant regardless shape functions of the cross-sectional depth. The shape functions are chosen as the linear, parabolic and sinusoidal ones. Ordinary differential equations governing free vibrations of such arches are derived and solved numerically for determining the natural frequencies. In the numerical examples, hinged-hinged, hinged-clamped and clamped-clamped end constraints are considered. As the numerical results, the relationships between non-dimensional frequency parameters and various arch parameters such as rise ratio, section ratio, side number, volume ratio and taper type are reported in tables and figures.

• Structural Engineering and Mechanics
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• 제55권4호
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• pp.785-799
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• 2015

A three-dimensional (3-D) method of analysis is presented for determining the free vibration frequencies of hyperboloidal shells free at the top edge and clamped at the bottom edge like a hyperboloidal cooling tower by the Ritz method based upon the circular cylindrical coordinate system instead of related 3-D shell coordinates which are normal and tangent to the shell midsurface. The Legendre polynomials are used as admissible displacements. Convergence to four-digit exactitude is demonstrated. Natural frequencies from the present 3-D analysis are also compared with those of straight beams with circular cross section, complete (not truncated) conical shells, and circular cylindrical shells as special cases of hyperboloidal shells from the classical beam theory, 2-D thin shell theory, and other 3-D methods.

• 소음진동
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• 제4권4호
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• pp.469-478
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• 1994

This paper desfcribes the formulation for the analysis of the free vibration of a circular cylindrical shell with elastic supports by the transfer influence coefficient method. This method was developed on the base of the concept of the successive transmission of dynamic influence coefficients. The analysis algorithm for circular cylindrical shell elastically restrained by springs, which plays an important role in many industrial fields, is discussed. The supporting springs have the axial, circumferential, radial and rotational spring constants uniformly distributed along the circumference of the shell. The simple computational results on a personal computer demonstrate the validity of the present method, that is, the numerical high accuracy, the high speed analysis method and the flexibility for programming, compared with results of the transfer matrixmethod and reference. We also confirmed that the present algorithm could obtain the solutions of high accuracy for system with a number of intermediate rigid supports. And we could easily treat the intermediate support and all boundary conditions by adequately varying the values of spring constants.

• Smart Structures and Systems
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• 제23권5호
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• pp.429-447
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• 2019

The present study analyzed free vibration of the three-layered micro annular/circular plate which its core and face sheets are made of saturated porous materials and FG-CNTRCs, respectively. The structure is subjected to magneto-electric fields and magneto-electro-mechanical pre loads. Mechanical properties of the porous core and also FG-CNTRC face sheets are varied through the thickness direction. Using dynamic Hamilton's principle, the motion equations based on MCS and FSD theories are derived and solved via GDQ as an efficient numerical method. Effect of different parameters such as pores distributions, porosity coefficient, pores compressibility, CNTs distribution, elastic foundation, multi-physical pre loads, small scale parameter and aspect ratio of the plate are investigated. The findings of this study can be useful for designing smart structures such as sensor and actuator.

• 대한기계학회논문집B
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• 제36권1호
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• pp.55-60
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• 2012

본 연구는 탄성 지지된 두 원기둥이 병렬로 배열되어 있을 때의 유력 진동 특성을 실험적으로 연구한 것이다. 구체적으로 2 원기둥의 각 간격(L/D, L:2 원기둥의 최단 거리, D:원기둥 직경)에서의 유속 변화에 따른 유력 진동 특성을 조사했다. 그리고 원기둥의 유력 진동 발생 메커니즘을 규명하기 위해 강제 진동 장치로 유력 진동을 정확히 재현한 가시화 실험을 하여 원기둥 주변의 흐름 패턴을 조사했다. 그 결과, 병렬 배열된 2 원기둥 사이의 스위칭 플로우의 변화에 따라 유력 진동 특성도 4 개의 패턴으로 변하는 것을 알 수 있었다. 그리고 직렬, 대각선, 병렬 배열된 2 원기둥 중에서 가장 유력 진동이 발생하기 쉬운 배열은 병렬 배열임을 본 연구를 통해 알 수 있었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 춘계학술대회 논문집
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• pp.690-691
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• 2014

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2010년도 춘계학술대회 논문집
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• pp.610-611
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• 2010