• Journal of Institute of Control, Robotics and Systems
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• v.8 no.4
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• pp.308-312
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• 2002

To determine the natural frequencies and damping ratios of composite laminated plates, we present an officient modal parameter estimation technique by developing residual spectrum based structural system reconstruction. The modal parameters can be estimated from poles and residues of the system transfer functions, derived from the state space system matrices. From vibration tests on cross-ply and angle-ply composite laminates, the natural frequencies and damping ratios can be estimated using the modal coordinates of the structural dynamic system reconstructed from the experimental frequency response functions. These results are compared with those of finite element analysis and single-degree-of-freedom curve fitting.

• Journal of KSNVE
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• v.8 no.2
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• pp.324-330
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• 1998

The forced vibration analysis of the outer-clamped spinnig annular disk with arbitrary in-plane is formulated to investigate the influence of non-uniform tension on the cutting accuracy of wafer cutting machine. The arbitrary in-plan force along the outer edge of an annular plate is expressed as a Fourier series. Galerkin method and modal superposition method are employed to obtain the forced responses under the static force and the impulse force in astationary coordinate. Through qualitative and quantitative analyses, it can be found that forced and impulse responses are sensitive to the non-uniformity of in-plane force, which can bring a bad effect to the accuracy of wafer cutting process. Also, in case of a spinning disk with non-uniform in-plane force, critical speed is required to define in a different way, compared with conventional definition in axi-symmetrical spinning disk.

• Journal of KSNVE
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• v.5 no.3
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• pp.373-383
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• 1995

From the viewpoint of the structural design, the principal problem of the heat exchanger is the potentiality of structural instabilities due to the fluid loading effect during operations. Excessive fluid loading may give rise to permanent deformation of tube and would enentually result in collapse of heat exchanger, which would cause an obstruction of the fluid flow in the narrow channels. In this study, a fluid-structural interaction model was developed to investigate analtically the vibration characteristics of thin rectangular tube used in the heat exchanger. The model consists of two flat plates separated by fluid. The effects of the fluid in the tube was stuided. For analyses, the natural frequency coefficients of the model were investigated for the plate aspect ratios, channel heights, and boundary conditions. As conclusions, the natural frequency coefficients of the tube is found to be affected largely by the fluid loading and the channel heights.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.896-901
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• 2002

The sound absorption coefficients for multiple layer perforated plate systems containing several compartments with airspaces and porous absorbing materials are estimated using the transfer matrix method developed in the previous paper. The absorption coefficients from transfer matrix method agree well with the values measured by the two-microphone impedance tube method for various combinations of perforated plates, airspaces or porous materials. Based on these results, a guidance for the design of multiple layer perforated plate systems combined with airspaces and porous absorbing materials is discussed in detail.

• Advances in aircraft and spacecraft science
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• v.5 no.6
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• pp.691-729
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• 2018

In this paper the hygro-thermo-mechanical vibration and buckling behavior of embedded FG nano-plates are investigated. The Eringen's and Gurtin-Murdoch theories are applied to study the small scale and surface effects on frequencies and critical buckling loads. The effective material properties are modeled using Mori-Tanaka homogenization scheme. On the base of RPT and HSDPT plate theories, the Hamilton's principle is employed to derive governing equations. Using iterative and GDQ methods the governing equations are solved and the influence of different parameters on natural frequencies and critical buckling loads are studied.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.388.1-388
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• 2002

The sound absorption coefficients for multiple layer perforated plate systems containing several companments with airspaces and porous absorbing materials are estimated using the transfer matrix method developed in the previous paper. The absorption coefficients from transfer matrix method agree well with the values measured by the two-microphone impedance tube method fur various combinations of perforated Plates, airspaces or porous materials. (omitted)

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.681-688
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• 2006

This paper has the object of investigating natural frequencies of tapered thick plate on pasternak foundation by means of finite element method and providing kinetic design data for mat of building structures. Finite element analysis of rectangular plate is done by use of rectangular finite element with 8-nodes. In order to analysis plate which is supported on pasternak foundation. the Winkler parameter is varied with 10, $10^2,\;10^3$ and the shear foundation parameter is 5, 10. This paper is analyzed varying thickness by taper ratio. The taper ratio is applied as 0.0, 0.25, 0.5, 0.75, 1.0 respectively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1992.10a
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• pp.124-129
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• 1992

이동 집중력 및 집중질량에 의한 이동하중을 받는 직사각형 보강판에 대하 여 보강재효과집중 모델링방법에 의거하여 보강판을 등방성 박판 및 보강재 효과를 반영한 등가보요소로 이루어진 판-보 조합체로 유한요소 모델링하고 Newmark의 직접 시간적분법을 이용한 동응답 해석방법을 정식화하였다. 일 련의 수치계산 예를 통하여 본 연구에서 제시한 방법이 이동하중을 받는 보 강판의 동응답 해석문제에 효과적으로 적용될 수 있음을 확인하였다. 아울러 parametric study를 통하여 이동하중이 작용하는 보강판의 동응답특성은 이 동하중의 질량효과를 고려하는 경우와 고려하지 않는 경우 매우 달라지며, 이동하중에 의한 동적응답은 이동속도가 증가할수록 정하중에 의한 응답보 다 증폭되어 나타나고 증폭비율이 질량효과를 고려할 경우 훨씬 더 커짐을 확인하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.645-650
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• 2004

There have been lots of efforts to analyze the dynamic characteristics of mechanical systems. However, it is difficult to know the dynamic characteristics of mechanical systems composed of many parts with joints. Specially, in case of a bolted joint structure, no effective modeling method has been defined to acquire dynamic characteristics of the structure, using the finite element (FE) analysis. In this research, a linear dynamic model is developed for bolted joints and large interfaces using con frusta method and linear spring elements, respectively. The developed modeling method for bolted joints is verified based on the experimental result.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.817-824
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• 2000

It is essential to analyze structural vibrations due to turbulent wall pressure fluctuations over a body surface which moves through a fluid, because the vibrations can be a severe source of noise affecting to passengers in airplanes and SONAR performance. Generally, this kind of problems have been solved for very simplified models, e.g. plates, which can be applied to the wavenumber domain analysis. In this paper, a finite element modeling of the wall pressure fluctuations over arbitrary smooth surfaces is investigated. It is found that the modeled wall pressure fluctuation at nodes becomes uncorrelated at higher frequencies and at lower flow speeds, and the response is over-estimated due to the aliased power. Finally, the frequency range available for uncorrelated loading model and two power correction schemes are presented.