• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.656-661
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• 2005

An optimization formulation of unconstrained damping treatment on beams is proposed to minimize vibration responses using a numerical search method. The fractional derivative model is combined with RUK's equivalent stiffness approach in order to represent nonlinearity of complex modulus of damping materials with frequency and temperature. The loss factors of partially covered unconstrained beam are calculated by the modal strain energy method. Vibration responses are calculated by using the modal superposition method, and of which design sensitivity formula with respect to damping layout is derived analytically. Plugging the sensitivity formula into optimization software, we can determine optimally damping treatment region that gives minimum forced response under a given boundary condition. A numerical example shows that the proposed method is very effective in minimizing vibration responses with unconstrained damping layer treatment.

• 한국소음진동공학회논문집
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• 제13권8호
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• pp.651-657
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• 2003

A new mechanical-electrical hybrid passive damping treatment is proposed to improve the performance of structural vibration control. The proposed hybrid passive damping system consists of a constrained layer damping treatment and a shunt circuit. In a passive mechanical constrained layer damping, a viscoelastic material damping layer is used to control the structural vibration modes in high frequency range. The passive electrical damping is designed for targeting the nitration amplitude in the low frequency range. The governing equations of motion are derived through the Hamilton's principle. The obtained mathematical model Is validated experimentally. The presented theoretical and experimental techniques provide invaluable tools for controlling the multiple modes of a vibrating structure over a wide frequency band.

• Computers and Concrete
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• 제9권5호
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• pp.357-374
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• 2012

The aim of this paper is to develop a procedure able to calculate the long-term stress and strain patterns in modern prestressed composite structures which are largely influenced by creep and shrinkage and whose final static configuration is the result of many phases of loading and restraints conditions. The introduction of equivalent moduli, depending on the viscous and elastic features of materials, can guarantee a significant simplification of the problem presented above. The proposed calculation model has been used to design the "Quattroquercie Viaduct" located on the highway "A3" Salerno-Reggio Calabria, Italy.

• 한국소음진동공학회논문집
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• 제11권4호
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• pp.52-57
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• 2001

The flexural vibration of aluminum beams with active and passive constrained-layer damping has been investigated experimentally to design a structure with maximum possible damping capacity. Piezoelectric film is used as a sensor and piezoceramic as an actuator for the negative velocity feedback control. The experimental results are compared with those by the finite element analysis. This paper shows the effectiveness of active constrained-layer damping treatment through experiments, and we have carried out an experiment to study the effect of beam thickness.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.362-367
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• 2003

A new mechanical-electrical hybrid passive dam ping treatment is proposed to improve the performance of structural vibration control. The proposed hybrid passive damping system consists of a constrained layer damping treatment and a shunt circuit. In a passive mechanical constrained layer damping, a viscoelastic material damping layer is used to control the structural vibration modes in high frequency range. The passive electrical damping is designed for targeting the vibration amplitude in the low frequency range. The governing equations of motion are derived through the Hamilton's principle. The obtained mathematical model is validated experimentally. The presented theoretical and experimental techniques provide invaluable tools for controlling the multiple modes of a vibrating structure over a wide frequency band.

• 한국소음진동공학회논문집
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• 제26권3호
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• pp.235-241
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• 2016

Underwater weapon system is required to structurally strong material, since as it is directly exposed to external shock. It should also be using the lightweight material in order to take advantage of buoyancy. Composite materials meet these requirements simultaneously. Particularly in the case of submarine, composite materials are widely used. It is important to have a high strength enough to be able to withstand external shock, but it is also important to attenuate it. In a method for the shock damping, viscoelastic damping materials are inserted between the high strength composite material as a sandwich structure. Shock attenuation can be evaluated in the loss factor. In ASTM(American Society of Testing Materials), evaluation method of the loss factor of cantilever specimens is specified. In this paper, mode tests of the cantilever are performed by the ASTM standard, in order to calculate the loss factor of the viscoelastic damping material by the specified expression. Further, for verifying of the calculated loss factor, mode test of compound beams is carried out. In addition, the characteristics of the material were analyzed the effect on the loss factor.