• 제목/요약/키워드: vibration and loss factor analysis

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유한요소법을 이용한 샌드위치형 감쇠 보구조물의 진동해석 (Vibration Analysis of Damped Sandwich Beam Using Finite Element Method)

  • 서영수;정의봉;신준엽
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2005년도 춘계학술대회논문집
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    • pp.978-981
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    • 2005
  • The vibration analysis of damped sandwich beam is conducted using finite element method. The equation of motion presented by Mead and Markus is used to formulate FEM. Also as the thickness of the core in the damped sandwich beam goes to zero, conventional beam theory based on the transformed-section method and the equation of Mead and Markus are compared. According to the change of thickness and loss factor of the core, the forced frequency response of beam is calculated and discussed. And then using the half-power band width method, the damping ratio of each mode is calculated and discussed about each case.

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내부손실계수 측정을 위한 실험 방법 (Experimental Methods for the Measurement of Damping Loss Factors)

  • 김관주;최승권
    • 소음진동
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    • 제9권6호
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    • pp.1187-1192
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    • 1999
  • The purpose of this study is to determine the most appropriate experimental method of the measurement of "damping loss factors" (DLF) for the statistical energy analysis(SEA) calculation. The successful prediction of vibration levels from the structure is critically dependent on the accurate estimation of DLF's not only in conventional vibration analysis but especially in SEA. Unforunately, calculation of accurate DLF is not an easy matter. So experimental methods are made use of for the DLF values. Three kinds of experimental methods for estimating DLF, i.e. decay rate method, half-power bandwidth method and power balance method, are presented and tests are carried out for the plate and the cylindrical shell examples. Pro and con of each methods is reviewed. Finally, calculated DLF values are used for vibration level estimation using commercial SEA software and compared with measured vibration data.tion data.

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점탄성층을 삽입한 3층 적층보의 진동감쇠특성에 관한 연구 (A Study on the Characteristics of Vibration Damping of a Beam with Inserted Viscoelastic Layer)

  • 박응순;박세만;박명균;박상규
    • 소음진동
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    • 제7권3호
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    • pp.511-519
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    • 1997
  • For a number of years it has been known that flexural vibration in a beam and plate can be damped by the application of layer of damping (viscoelastic) material that is in turn constrained by a backing layer or foil. In this study, a quantitative analysis of damping of the sandwich beam has been performed by using impact test. The damping is characterized by the loss factor .etha. in which the damping is normalized by imaginary part of the complex bending stiffiness of the beam. Results show that the relative thickness of the sandwich beam gives more effect on the riatural-frequencies and loss factor than the variation of width does. It is also shown that the Ross-Kerwin-Ungar equation and impact test can be effectively used to identify the damping characteristic of the sandwich beam and viscoelastic material.

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Damping and vibration response of viscoelastic smart sandwich plate reinforced with non-uniform Graphene platelet with magnetorheological fluid core

  • Eyvazian, Arameh;Hamouda, Abdel Magid;Tarlochan, Faris;Mohsenizadeh, Saeid;Dastjerdi, Ali Ahmadi
    • Steel and Composite Structures
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    • 제33권6호
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    • pp.891-906
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    • 2019
  • This study considers the instability behavior of sandwich plates considering magnetorheological (MR) fluid core and piezoelectric reinforced facesheets. As facesheets at the top and bottom of structure have piezoelectric properties they are subjected to 3D electric field therefore they can be used as actuator and sensor, respectively and in order to control the vibration responses and loss factor of the structure a proportional-derivative (PD) controller is applied. Furthermore, Halpin-Tsai model is used to determine the material properties of facesheets which are reinforced by graphene platelets (GPLs). Moreover, because the core has magnetic property, it is exposed to magnetic field. In addition, Kelvin-Voigt theory is applied to calculate the structural damping of the piezoelectric layers. In order to consider environmental forces applied to structure, the visco-Pasternak model is assumed. In order to consider the mechanical behavior of structure, sinusoidal shear deformation theory (SSDT) is assumed and Hamilton's principle according to piezoelasticity theory is employed to calculate motion equations and these equations are solved based on differential cubature method (DCM) to obtain the vibration and modal loss factor of the structure subsequently. The effect of different factors such as GPLs distribution, dimensions of structure, electro-magnetic field, damping of structure, viscoelastic environment and boundary conditions of the structure on the vibration and loss factor of the system are considered. In order to indicate the accuracy of the obtained results, the results are validated with other published work. It is concluded from results that exposing magnetic field to the MR fluid core has positive effect on the behavior of the system.

바닥충격음 완충재의 동적특성에 영향을 미치는 요인 분석 (Analysis of Influence Factors on Dynamic Properties of Floor Impact Noise Insulation Materials)

  • 김흥식;주시웅;김대준;김병진
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2005년도 추계학술대회논문집
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    • pp.946-949
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    • 2005
  • In this paper, influence factors on dynamic properties of floor impact noise insulation materials are suggested. For this purpose measurements on the dynamic stiffness and the loss factor of resilient materials are carried out by Korea standard (KS F 2868) according to the change of density, thickness, design pattern, and composition of materials. As a result the values of dynamic stiffness was decreased at high density and thick thickness, and that of loss factor was increased at low density. For dynamic properties, the pattern of lattice and waffle type material is better than that of plat type, and the mixed composition of materials is better than the composition of double layer materials at same thickness.

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자동차용 흡.차음재의 성능분석을 위한 통계적 에너지 기법의 적용 (An Application of the Statistical Energy Analysis for Absorbing and Soundproofing Materials of Vehicle)

  • 이장명;이준;김대곤
    • 한국소음진동공학회논문집
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    • 제13권1호
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    • pp.33-39
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    • 2003
  • Interior parts of a vehicle are getting important to reduce interior noise. Therefore, prior analysis of cabin noise related with interior parts are necessary at first design stage. Recently, Statistical Energy Analysis(SEA) has been suggested as a possible way for high frequency range noise analysis of interior parts. The validity of noise analysis with SEA to interior parts has been preyed by comparing with experimental result, and the developed method with SEA has been applied in finding optimized interior parts package.

점탄성층이 부분적으로 삽입된 샌드위치보의 횡진동 특성 (Behavior of the Flexural Vibration of a Sandwich Beam with Partially Inserted Viscoelastic Layer)

  • 박진택;최낙삼
    • 한국복합재료학회:학술대회논문집
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    • 한국복합재료학회 2000년도 춘계학술발표대회 논문집
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    • pp.167-170
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    • 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.

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자동차용 흡.차음재의 성능분석을 위한 통계적 에너지 기법 적용의 검정 (An application of the Statistical Energy Analysis for Absorbing and Soundproofing Materials of Vehicle)

  • 이장명;이준;김대곤;정병인
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2001년도 추계학술대회논문집 II
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    • pp.1109-1113
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    • 2001
  • Interior parts of a vehicle are getting important to reduce interior noise of car. Therefore, prior analysis of cabin noise related with interior parts are necessary at first design stage. Recently, Statistical Energy Analysis(SEA) has been suggested as a possible way for meddle of high frequency range analysis with interior parts. This article introduces an example of the application of SEA to predict air born noise of cabin of car.

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압전 지능 구조물을 이용한 통계적 에너지 해석 기법 (Application of Piezoelectric Smart Structures for Statistical Energy Analysis)

  • 김재환;김정하;김재도
    • 소음진동
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    • 제11권2호
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    • pp.257-264
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    • 2001
  • In this research, piezoelectric smart structures are applied for SEA(Statistical Energy Analysis), which is well known approach for high frequency analysis. A new input power measurement based on piezoelectric electrical power measurement is proposed and compared with the conventional method in SEA. As an example, a simple aluminum beam on which piezoelectric actuator is attached is considered. By measuring the electrical impedance and electrical current of the piezoelectric actuator, the electrical power given on the actuator is found and this is In turn converted into the mechanical energy. From the measured value of the stored energy of the beam, the Internal loss factor is calculated and this value shows a good agreement with that given by the conventional method as well as the theoretical value. To compare the coupling loss factor, L-shape beam system which consists of a aluminum beam subsystem and a steel beam subsystem coupled by three pin is taken as second example. The input power and stored energy of each subsystem are found by the proposed approach. The coupling loss factor found by the electrical input power obtained from the piezoelectric actuator exhibits similar trend to the value found by the conventional method as well as the theoretical value. In conclusion, the use of SEA for high frequency application of piezoelectric smart structures is Possible. Especially, the input power that is essential for SEA can be found accurately by measuring the electrical input power of the piezoelectric actuator.

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통계적 에너지 해석 기법에 의한 밀폐형 회전 압축기의 소음진동 전달경로 해석 (A Study on the Noise and Vibration Path of Hermetic Rotary Compressor by SEA)

  • 황선웅;안병하;정현출;정의봉;김규환
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2002년도 추계학술대회논문집
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    • pp.869-874
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    • 2002
  • Hermetic rotary compressor is one of the most important components for air conditioning system since it has a great effect on both the performance and the noise and vibration of the system. Noise and vibration of rotary compressor is occurred due to gas pulsation during compression process and unbalanced dynamic force. In order to reduce noise and vibration, It is necessary to identify sources of noise and vibration and effectively control them. Many approaches have been tried to identify noise sources of compressor. However, compressor noise source identification has proven to be difficult since the characteristics of compressor noise are complicated due to the interaction of the compressor parts and gas pulsation. In this work, Statistical Energy Analysis has been used to trace the energy flow in the compressor and identify transmission paths from the noise source to the sound field.

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