• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1149-1152
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• 2007

Many kind of damping materials are generally used on concrete slab in apartment building to reduce floor impact noise level. Lately, multi-layered damping material that is consist of several materials are used to improve the effect of floor impact noise insulation. In this study, dynamic stiffness of multi-layered damping material that is consist of common materials such as expanded polystyrene(EPS), expended polyethylene(EPE), ethylene vinyl acetate(EVA) and polyester was investigated. It was found that dynamic stiffness of multi-layered damping material could be estimated if know value of each layer that compose whole structure. And it was found that dynamic stiffness of whole structure did not change even if change order that build layer.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.29-32
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• 2005

Based on the full layerwise displacement shell theory, vibration and damping characteristics of cylindrical sandwich panels are investigated. The transverse shear deformation and the normal strain are fully taken into account for structural damping modelling. Modal damping factors and frequency response functions are analyzed for various structural parameters of cylindrical sandwich beams. Present results shows that full layerwise theory can accurately predict vibration and damping characteristics of cylindrical composite panels with surface damping treatments and constrained layer damping. The viscoelastic materials depending on elevated temperature environment and exciting frequencies can be fully considered.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.1192-1196
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• 2001

Damping materials show variant characteristics depend on frequency or temperature condition. Therefore, we need to measure damping material characteristics called a loss factor or a young's modulus varying frequency or temperature condition. In this article, measuring procedure and method has been introduced for damping material using a sticking damping material with a thin steel beam. And it shows a temperature effect to damping materials.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.377-380
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• 2005

Damping materials encompass a broad range of materials, including, but not limits to, pressure sensitive adhesives, epoxies, rubbers, foams, thermoplastics, enamels and mastics. Their common characteristic is that their modulus is represented by a complex quantity, possessing both a stored and dissipative energy component. Loss factor of damping material analyzed more than 2 times than rubber to 1.5 $\sim$ 2.3, could know that Damping layer has excellent attenuation performance in side of vibration reduction. Measurements of vibration using accelerometers by adhesion of Damping layer, square Plate by Separation of Damping layer is less binding of Damping layer, analyzed low loss factor and Natural Frequency by free Vibration of Square Plate.

• Proceedings of the Korean Magnestics Society Conference
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• 2009.12a
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• pp.89-90
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• 2009

To summarize, we observed a spatial distribution of damping tensor gives a different simulation result. When we use LLG equation, especially dealing with spatially-varying magnetization texture, it is expected that damping tensor should be considered instead of constant damping.

• Smart Structures and Systems
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• v.20 no.3
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• pp.263-272
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• 2017

This paper presents the time response of a mixed vibration system with the viscous damping and the hysteretic damping. There are two ways to derive the time response of such a vibration system. One is an analytical method, using the contour integral of complex functions to compute the inverse Fourier transforms. The other is an approximate method in which the analytic functions derived by Hilbert transform are expressed in the state space representation, and only the effective eigenvalues are used to efficiently compute the transient response. The unit impulse responses of the two methods are compared and the change in the damping properties which depend on the viscous and hysteretic damping values is investigated. The results showed that the damping properties of a mixed damping vibration system do not present themselves as a linear combination of damping properties.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.1072-1076
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• 2004

In automotive industry, all passenger vehicles are treated with damping materials to reduce structure borne noise. The effectiveness of damping treatments depends upon design parameters such as choice of damping materials. locations and size of the treatment. Generally, the CAE method uses modal strain-energy information of the bare structural panels to identify flexible regions, which in turn facilitates optimization of damping treatments with respect to location and size. This paper proposes a design of the damping material with a CAE(Computer Aided Engineering) methodology based on finite element analysis and DOE(Design Of Experiments) to optimize damping treatments.

• Korean Journal of Materials Research
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• v.28 no.10
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• pp.583-589
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• 2018

This study investigates the effect of fatigue stress on the damping capacity in a damaged Fe-22Mn-12Cr-3Ni-2Si-4Co damping alloy under fatigue stress. ${\alpha}^{\prime}$ and ${\varepsilon}-martensite$ forms by fatigue stress in the damaged Fe-22Mn-12Cr-3Ni-2Si4-Co damping alloy under fatigue stress. The ${\alpha}^{\prime}$ and ${\varepsilon}-martensite$ forms with the specific direction and surface relief, or they cross each other. With an increasing fatigue stress, the volume fraction of ${\alpha}^{\prime}-martensite$ and ${\varepsilon}-martensite$ increases. With an increasing fatigue stress, the damping capacity increases with an increase in the volume fraction of ${\varepsilon}-martensite$. The increase in the damping capacity in the damaged Fe-22Mn-12Cr-3Ni-2Si-4Co alloy under fatigue stress strongly affects the increase of ${\varepsilon}-martensite$ formed by fatigue stress, but the damping capacity of the damaged Fe-22Mn-12Cr-3Ni-2Si-4Co damping alloy under fatigue stress is strongly controlled by a large amount of ${\alpha}^{\prime}-martensite$.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.206-210
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• 2003

Machining of deep holes with conventional boring bars frequently induce chatter vibration because of their low dynamic stiffness which is defined as the product of static stiffness and damping of conventional boring bar materials. In addition, the specific stiffness ($E/{\rho}g$) of boring bars is more important than the static stiffness to increase the fundamental natural frequency of boring bars in high speed machining. Therefore, boring bar materials should have high static stiffness and high damping as well as high specific stiffness. The best way to meet requirements is to employ fiber reinforced composite materials for high speed boring bars because composite materials have high static stiffness, high damping and high specific stiffness compared to conventional boring bar materials. In this study, the dynamic characteristics of carbon fiber epoxy composite boring bars were investigated. From the metal cutting test, it was found that the chatter was not initiated up to the ratio of length to diameter of 10.7 at the rotating speed of 2,500 rpm.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.127-132
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• 2001

In this paper, transmitted sound reduction performance of smart panels is studied according to different piezoelectric materials with piezoelectric shunt damping. Peizo-damping is implemented by using a newly proposed tuning method. This method is based on electrical impedance model and maximizing the dissipated energy at the shunt circuit. By measuring the electrical impedance at the piezoelectric patch bonded on a structure, an equivalent electrical model is constructed near the system resonance frequency. After shunting elements are connected to the equivalent circuit, the shunt parameters are optimally searched based on the criterion of maximizing the dissipated energy at the shunt circuit. Transmitted sound reduction performance is compared according to different piezoelectric materials with peizo-damping. Two piezoelectric materials are selected: PZT-5 and QuickPack IDE actuator. When resonant shunt circuit is considered, the use of PZT-5 exhibited the good sound reduction performance.