• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2000.04a
• /
• pp.167-170
• /
• 2000

The flexural vibration of a sandwich beam with partially inserted viscoelastic layer has been studied using the finite element analysis in combination with an experiment. Effects of length and thickness of partial viscoelastic layers on system loss factor(${\eta}_s$) and resonant frequency(${\omega}_r$) were considerably large. The thicker the viscoelastic layer in a sandwich beam, the larger the system loss factor in Mode 1 as compared with that in Mode 2. The loss factor increased almost linearly with increasing the length of partial viscoelastic layer. Effects of thickness of beams were also considered.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.11a
• /
• pp.1160-1166
• /
• 2007

In this study, a new slab system that adjoint precast slabs are connected each other by viscoelastic material is proposed and numerical analysis is performed to evaluate the effect of the slab system on the vibration and noise control. Substructuring is introduced to develope the equation of motion of the slab system and the optimal properties of viscoelastic material are calculated. For the performance evaluation of the new slab system, the sound power and acceleration of the slab are compared with those of two way slab and the slab which the viscoelastic material is not connected. Numerical results show that the sound power of the new slab system can be reduced an amount of 6dB.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.32 no.7
• /
• pp.487-496
• /
• 2008

Quartz crystal oscillator is frequently used in measuring a very small amount of mass attached to or adsorbed on the surface of an electrode on the quartz plate. The physical principle is that the resonance frequency of the shear vibration of the quartz caused by an applied electric field is a function of the mass. Recently, effort has been tried to measure physical properties of viscoelastic fluids, such as viscosity and shear modulus. This paper presents useful formula that can be used in estimating the properties of viscoelastic fluids. Important finding in this analysis is that the formula can produce multiple values for the physical properties of the viscoelastic materials.

• Korea-Australia Rheology Journal
• /
• v.14 no.4
• /
• pp.203-207
• /
• 2002

Particle-particle interaction is of great importance in the study of suspension rheology. In this research we have investigated the hydrodynamic interaction between two identical cylinders in viscoelastic fluids numerically as a model problem for the study of viscoelastic suspension. We confine two neutrally buoyant cylinders between two parallel plates and impose a shear flow. We determine the migration velocity of two cylinders. The result shows that cylinders move toward or away from each other depending upon the initial distance between them and that there is an equilibrium distance between two cylinders in viscoelastic fluids regardless of the initial distance. In the case of Newtonian fluid, there is no relative movement as expected. The results partly explain the chaining phenomena of spherical particles in shear flows of viscoelastic fluids.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.11b
• /
• pp.605-610
• /
• 2002

Eigenvalues are taken as performance criteria for structural damping design using viscoelastic material. Given material properties, optimal distribution of damping material is sought based on eigenvalue sensitivity. For eigenanalysis of frequency dependent viscoelastic material treated structures, Golla-Mushes-McTavish (GHM) model is used and some dominant modes are chosen for consideration. To avoid the intensity of computation caused by increased problem size, an alternative approximate method is proposed which uses elastic modes and can be applied under small damping assumption. A cantilever beam treated with unconstrained viscoelastic layer is tested and optimal distribution of thickness of the layer is illustrated. Partial coverage configurations are compared with the one-sided full coverage case.

• Structural Engineering and Mechanics
• /
• v.61 no.2
• /
• pp.221-230
• /
• 2017

In this paper, we investigated the propagation of thermoelastic surface waves in fibre-reinforced anisotropic general viscoelastic media of higher order of nth order including time rate of strain under the influence of rotation. The general surface wave speed is derived to study the effectsof rotation andthermal onsurface waves. Particular cases for Stoneley, Love and Rayleighwaves are discussed.The results obtained in this investigation are more general in the sense that some earlier published results are obtained from our result as special cases. Our results for viscoelastic of order zero are well agreed to fibre-reinforced materials. Comparison was made with the results obtained in the presence and absence of rotation and parameters for fibre-reinforced of the material medium. It is also observed that, surface waves cannot propagate in a fast rotating medium.Numerical results for particular materials are given and illustrated graphically. The results indicate that the effect of rotation on fibre-reinforced anisotropic general viscoelastic media are very pronounced.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.1 no.3
• /
• pp.11-19
• /
• 1997

In this paper, an efficient dynamic analysis method of a building structure with viscoelastic dampers is proposed. Viscoelastic dampers are used for the purpose of controlling vibration of buildings. The matrix condensation technlque based on the rigid diaphragm assumption is not readily applicable for building structures with viscoelastic dampers. An improved procedure for damping matrix condensation is employed in the proposed method to increase the efficiency of analysis. Efficiency and accuracy of the proposed method are verified through analysis of an example structure.

• Journal of Ocean Engineering and Technology
• /
• v.12 no.2 s.28
• /
• pp.22-32
• /
• 1998

Many of steel structures having little internal damping consist of stiffened plates. In case that viscoelastic materials are adhered to the stiffened plates for the reduction of structure-borne noise, their effects are varied by the adhered position and dynamic characteristics of the structures as well as their material properties and adhered amount. In this paper, sound reduction effects of viscoelastic materials partially adhered to the different positions of a stiffened steel plate have been investigated by the measurement of vibratory velocity and sound intensity. The results show that optimal adherent positions of viscoelastic materials to reduce sound radiation power are the loop areas of modes.

• 한국전산유체공학회:학술대회논문집
• /
• 1998.11a
• /
• pp.114-120
• /
• 1998

The present numerical study investigates flow characters and heat transfer enhancement by the viscoelastic-driven secondary flow and buoyancy effect in a 2:1 rectangular duct. Three versions of thermal boundary conditions involving difference combination of heated walls and adiabatic walls are analyzed in this study. The Reiner-Rivlin model is adopted as a viscoelastic fluid model to simulate the secondary flow and temperature-dependent viscosity model is used. Calculated Nusselt numbers are very good agreement with experimental results for reported viscoelastic fluids. It is found that the heat transfer enhancement is mainly caused by the viscoelastic-driven secondary flow and buoyancy-induced secondary flow play a role of promoting this effect.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.1030-1035
• /
• 2003

The nanoimprint lithography technology makes higher density of semiconductor device and larger capacity of storage media. In this technology the induced damage while detaching polymer pattern from mold should be minimized. In order to analyze the problem, the basic knowledge of adhesion between the polymer and the mold is required. In this study a contact experiment of polyisobutylene specimen with spherical steel tip and polyisobutylene bead tip was conducted using nano indenter. During the contact experiment with various loading rate under load control the contact behavior of viscoelastic material was measured, i.e., the load and displacement between the tip and the specimen were measured. The data was analyzed by HBK model to obtain the stress intensity factor of contact edge and the contact radius as a function of time. Also the adhesion energies between steel/polyisobutylene and polyisobutylene/polyisobutylene were obtained employing the analysis of the crack of viscoelastic material by Schapery.