• Title/Summary/Keyword: vibration and loss factor analysis

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Vibration Power Flow Analysis of Coupled Shell Structures (연성된 쉘 구조물의 진동 파워흐름해석)

  • Kim, Il-Hwan;Hong, Suk-Yoon;Park, Do-Hyun;Kil, Hyun-Gwon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.11b
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    • pp.492-497
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    • 2002
  • In this paper, Power Flow Analysis(PFA) method has been applied to the prediction of vibration energy density and intensity of coupled shell structures in the medium-to-high frequency ranges. To consider the wave transformation at joint between shell elements, power transmission and reflection coefficients are investigated for various joint angles, and here Donnell-Mushtari thin shell theory has been used. For validations computations are performed to analyze the response of coupled shells by changing the excitation frequency and damping loss factor.

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Analysis of Mount Reaction Forces for Powertrain Mounting Systems using Nonlinear Characteristics (비선형 특성을 적용한 파워트레인 마운팅 시스템의 마운트 전달력 해석)

  • Kim, J.H.;Lee, S.J.;Lee, W.H.;Kim, J.R.
    • Journal of Power System Engineering
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    • v.12 no.2
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    • pp.23-28
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    • 2008
  • The primary objective of this study is to truly understand reaction force be due to engine exciting force. Exciting forces of the engine apply a source of the vehicle NVH(Noise, Vibration, Harshness). To understand reaction force was applied MSC.Nastran software. Analyzed frequency response analysis of powertrain mount system. First, engine exciting force was applied field function. Also nonlinear characteristics was applied field function : such as dynamic spring constant and loss factor. And nonlinear characteristics was applied CBUSH. Generally characteristics of rubber mount is constant frequency. But characteristics of hydraulic mount depend to frequency. Therefore nonlinear characteristics was applied. Powertrain mounting system be influenced by powertrain specification, mount position, mount angle and mount characteristics etc. In this study, we was analyzed effects of powertrain mounting system. And we was varied dynamics spring constant and loss factor of mounts.

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Exhaust Noise Reduction of Dry vacuum Pump (건식진공펌프의 배기 소음 저감)

  • Ahn, Young-Chan;Lee, Hae-Jin;Lee, Jung-Yoon;Yang, Jung-Jik;Oh, Jae-Eung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.05a
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    • pp.349-354
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    • 2007
  • This paper considers acoustic analysis of silencer within a Dry vacuum pump. Main object is noise reduction of Dry Vacuum Pump using the silencer. First, we measured SPL and Intensity for noise source identification and then, designed for the silencer corresponding with noise character. 4-pole parameter are used for predicting transmission loss which is one of characteristics of silencer when we designed for silencer. Calculated Transmission Loss to change main effective factor and selected to optimal value using Design of Experiment. Finally, noise reduction is estimated to compare existing silencer with optimal silencer.

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Parameter Design of an ER Panel for Noise Reduction using Taguchi Method (다구찌법을 이용한 소음저감용 ER 패널의 파라미터 설계)

  • 윤영민;김재환;최승복
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.638-642
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    • 2003
  • This paper presents a parameter design of an Electrorheological(ER) panel for noise reduction using Taguchi method. Taguchi method is a robust design method that determines control parameters in the presence of noise effect. Host structure thickness, spacer thickness, base oil viscosity and the weight ratio of ER particles are chosen for the control factors. A test setup in an SAE J1400 facility is used to analyze the sound transmission loss. The sensitivity of each factor with signal-to-noise(S/N) ratio and analysis of variance are investigated. The analysis results show that the weight ratio of ER particle and base oil viscosity of the ER fluid mostly affects the noise reduction in the presence of electric field. Based on the Taguchi method, an optimal configuration was designed and comparison is made with experimental result fer the verification.

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An Experimental Study on the Measurement of Elastic and Damping Coefficients of a Composite Material (복합재의 탄성 및 감쇠계수 측정을 위한 실험연구)

  • Park, Han-Il;Shon, Jae-Geon;Min, Cheon-Hong;Bae, Soo-Ryong
    • Journal of the Society of Naval Architects of Korea
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    • v.44 no.1 s.151
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    • pp.26-31
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    • 2007
  • Understanding viscoelastic properties of composite materials is essential for the design and analysis of composite structures. Specially, the loss factor and Young's modulus must be known to develop finite element codes for a composite structure with several damping materials. In this study, an advanced technique for obtaining accurate loss factor and Young's modulus of a composite structure is introduced based on the method of American Society for Testing and Materials (ASTM). The loss factor and Young's modulus of a composite structure are measured for different temperatures by performing the test in a vibration measurement room where temperature can be controllable from 5 to 45 Celsius.

Analysis of the Vibration Transmitting Characteristics of the Insulation-foam for Reducing Refrigerant-induced Noise of a Refrigerator (냉장고 냉매소음 저감을 위한 단열 발포재의 진동 전달특성 분석)

  • Han, Hyung-Suk;Kim, Min-Sung;Jeong, Weui-Bong;Seo, Min-Young;Lee, Soo-Young
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.20 no.1
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    • pp.45-50
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    • 2010
  • In the refrigerator, the two-phase refrigerant-induced noise of the capillary tube in an evaporator-inlet pipe has been a great concern. The capillary tube is usually covered with insulation-foam packed in the space between inner and outer cabinets without any vibration isolation. Therefore, the refrigerant-induced vibration of the capillary tube can be easily transferred to the outer cabinet, which may increase the radiated noise. In this paper, the characteristics of transferred vibration through the insulation-foam are investigated experimentally by using the refrigerantsupplying equipment. The frequency characteristics, such as dynamic Young's modulus and loss factor, of the insulation-foam are also discussed.

Vibration characteristic analysis of sandwich cylindrical shells with MR elastomer

  • Yeh, Jia-Yi
    • Smart Structures and Systems
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    • v.18 no.2
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    • pp.233-247
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    • 2016
  • The vibration characteristic analysis of sandwich cylindrical shells subjected with magnetorheological (MR) elastomer and constraining layer are considered in this study. And, the discrete finite element method is adopted to calculate the vibration and damping characteristics of the sandwich cylindrical shell system. The effects of thickness of the MR elastomer, constraining layer, applied magnetic fields on the vibration characteristics of the sandwich shell system are also studied in this paper. Additionally, the rheological properties of the MR elastomer can be changed by applying various magnetic fields and the properties of the MR elastomer are described by complex quantities. The natural frequencies and modal loss factor of the sandwich cylindrical shells are calculated for many designed parameters. The core layer of MR elastomer is found to have significant effects on the damping behavior of the sandwich cylindrical shells.

Flexural Vibration Analysis of a Sandwich Beam Specimen with a Partially Inserted Viscoelastic Layer

  • Park, Jin-Tack;Park, Nak-Sam
    • Journal of Mechanical Science and Technology
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    • v.18 no.3
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    • pp.347-356
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    • 2004
  • The flexural vibration characteristics of a sandwich beam system with a partially inserted viscoelastic layer were quantitatively studied using the finite element analysis in combination with the sine-sweep experiment. Asymmetric mode shapes of the flexural vibration were visualized by holographic interferometry, which agreed with those obtained by the finite element simulation. Effects of the length and the thickness of the partial viscoelastic layer on the system loss factor (η$\_$s/) and resonant frequency (f$\_$r/) were significantly large for both the symmetric and asymmetric modes of the beam system.

Multiple-Mode Vibration Control Using Piezoelectric Shunted Actuator (압전 분기회로를 이용한 다중모드제어)

  • 박철휴
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.05a
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    • pp.202-207
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    • 2002
  • This paper deals with a novel shunted actuator, which has a capability to suppress multi-mode vibration amplitudes by using a pair of piezoceramic patches. In order to describe the characteristic behaviors of shunted dampers connected with a series and a parallel resistor-negative capacitive branch circuit, the stiffness ratio and loss factor with respect to the non-dimensional frequency are considered. To obtain a guideline model of a piezo/beam system connected with a series and a parallel resistor-negative capacitor branch circuit, the governing equations of motion is derived through Hamiltons principle and a piezo sensor equation as well as a shunt damping matrix is developed. The theoretical analysis shows that the shunted actuator developed in this study can significantly reduce multiple-mode vibration amplitudes simultaneously over the whole structural frequency range.

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Vibration and Damping Characteristic of Composite Laminates Embedding Directional Damping Materials (방향성 있는 감쇠재료가 삽입된 복합적층판의 진동 및 감쇠특성)

  • 김성준
    • Composites Research
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    • v.16 no.5
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    • pp.39-44
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    • 2003
  • Embedding viscoelastic-damping materials into composites can greatly increase the damping properties of composite structures. Usually viscoelastic-damping materials behave isotropically so that their damping properties are the same in all directions. In these days, there is a desire to develop viscoelastic-damping materials that behave orthotropically so that damping properties vary with material orientation. These orthotropic damping materials can be made by embedding rows of thin wires within the viscoelastic materials. These wires add significant directional stiffness to the damping materials. where the stiffness variation with wire orientation follows classical lamination theory. In this paper, the loss factor of composite laminate was evaluated based on Ni and Adams' theory. To investigate the effect of directional damping material, the low-velociy impact response analysis was also performed. The present analysis results show that directional damping material has a great influence on vibration and damping characteristic of composite laminate.