• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.219-224
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• 2012

In this paper, vibration and flow-induced flutter instability analysis of cantilever multiwall carbon nanotubes conveying fluid and modelled as a thin-walled beam is investigated. Non-classical effects of transverse shear and rotary inertia are incorporated in this study. The governing equations and the associated boundary conditions are derived through Hamilton's principle. Numerical analysis is performed by using extend Galerkin method which enables us to obtain more exact solutions compared with conventional Galerkin method. Cantilevered carbon nanotubes are damped with decaying amplitude for flow velocity below a certain critical value, however, beyond this critical flow velocity, flutter instability may occur. Variations of critical flow velocity with both radius ratio and length of carbon nanotubes are investigated and pertinent conclusion is outlined.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.693-699
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• 2011

The outermost SG tubes have more structural problems than inside tubes. Many studies have used a uniform added mass coefficient for all of the SG tubes during the FIV analysis. The purpose of this study is to find out the added mass coefficients for each tube in a cylindrical shell. When a number of tubes are increased, added mass coefficients are also increased. And added mass coefficients at outermost tubes are less than those of inside tubes. According to gap changes between outermost tube and cylindrical shell, added mass coefficients are decreased with increasing the gap. When the gap has very large value, it shows that the added mass coefficient is asymptotically converged to the value of the tube array in a free fluid field.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.916-921
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• 2006

Column mixer is one of the facility to mix fluids at petrochemical plants. The column vibration is caused by pumps for fluid inflow and mixing of inside fluids. This fluid induced vibration is mainly responsible for the reduction of column life. Measurements were performed three times for understanding the vibration characteristics of the column. First experimental results showed the need of stiffness reinforcement. After the reinforcement work, second measurement conformed the difference between two results. Modal analysis was also performed to investigate the resonance of the column vibration and the damage of the rib plate. To confirm the generation of the fluid instability in the column mixer fluid structure interaction analysis using ADINA/FSI was performed which showed the necessity of the modification of the rotary valve.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.9
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• pp.439-453
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• 2001

This study deals with the free vibration of two identical circular plates coupled with a bounded fluid. An analytical method based on the finite Fourier-Bessel series expansion and Rayleigh-Ritz method is suggested. In the theory, it is assumed that the ideal fluid in a rigid cylindrical container and the two plates are clamped along the plate edges. The proposed method is verified by the finite element analysis using commercial program with a good accuracy. Two transverse vibration modes, namely in-phase and out-of-phase, are observed alternately in the fluid-coupled system when the number of nodal circles increases for the fixed nodal diameter. The effect of gap between the plates on the fluid-coupled natural frequencies sis also investigated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.1077-1082
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• 2004

It is well known that the pipe will be unstable if the fluid velocity is higher than critical velocity. But even if the velocity of the fluid below the critical velocity, resonance will be caused by pulsation of the fluid. So, many people has studied about the piping system vibration due to a fluid pulsation. But almost guess that fluid has only one hamonic pulsation. Actually, like this case is rare quite. So, in this paper, we consider the vibration analysis of a pipe conveying fluid with several harmonic pulsations and compare the result which considers one hamonic pulsation with the result which considers several harmonic pulsations. And we verify the result in time domain again.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.359-362
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• 2009

Damping characteristics of pressure oscillation induced by an orifice in fluid feeding line for are investigated numerically and experimentally. Assuming small pressure oscillation, acoustic damping effect of orifice is confirmed experimentally, and with the mean flow, damping characteristics of an orifice are investigated numerically. When an orifice is installed at the node of pressure oscillation corresponding to the anti-node of velocity oscillation, suppression of pressure oscillation is maximized and with the mean flow, the resonant frequency is decreased. And, it is found that the optimal position of an orifice for damping shouled be changed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.10
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• pp.1049-1056
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• 2008

A method for the vibration analysis of curved beam conveying fluid with uniform velocity was presented. The dynamics of curved beam is based on the inextensible theory. Both in-plane motion and out-of-plane motion of curved beam were discussed. The finite element method was formulated to solve the governing equations. The natural frequencies calculated by the presented method were compared with those by analytical solution, straight beam theories and Nastran. As the velocity of fluid becomes larger, the results by straight beam model became different from those by curved beam model. And it was shown that the curved beam element should be used to predict the critical velocity of fluid exactly. The influence of fluid velocity on the frequency response function was also discussed.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.4 s.142
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• pp.396-401
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• 2005

In this study, the assumed mode method using characteristic polynomials of Timoshenko beam is applied to the free vibration analysis for the stiffened plate of ship tank side in contact with water. The hydro-elastic effect of the fluid-structure interaction is considered by fluid velocity potential, derived from boundary conditions for fluid and structure, and utilized in the calculation of added mass matrix using assumed modes. To verify the validity and effectiveness of the presented method, free vibration analysis for the stiffened plates in contact with finite and infinite fluids have been carried out and its results were compared with those obtained by a general purpose FEA software.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.4
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• pp.291-298
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• 2011

According to the developments of automobile industry, the technology to enhance noise, vibration and harshness(NVH) performance has been studying in a point of view of ride comfort and quietness. Especially the use of computer aided engineering(CAE) simulation tools such as finite element(FE) analysis allows engineers to efficiently evaluate NVH performance. This paper presents the method to bulid FE models for full vehicle including engine, transmission. suspension and steering system, also to evaluate vibration performance of full vehicle. The full vehicle model, which is discussed, is correlated with the result of the frequency response measurement in the case of the car shake performance for high speed driving.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.921-925
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• 2003

An analytical method for the free vibration of single circular plate submerged in a fluid-filled rigid cylindrical vessel was developed by the Rayleigh-Ritz method based on the Fourier-Bessel series expansion. It was assumed that the plate is clamped at an offcentered location of the cylinder, and the non-viscous incompressible fluid contained in the cylinder is bisected by the plate. It was found that the theoretical results can predict well the fluid-coupled natural frequencies with excellent accuracy comparing with the finite element analysis results. The offcentered distance effect on the natural frequencies was also observed.