• Title/Summary/Keyword: radiated sound power

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Reduction of Sound Radiated Power of Clamped Beams using Filtered Velocity Feedback Controllers (Filtered Velocity Feedback 제어기를 이용한 양단지지보의 음향파워 저감)

  • Shin, Chang-Joo;Hong, Chin-Suk;Jeong, Weui-Bong
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.21 no.12
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    • pp.1104-1111
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    • 2011
  • This paper investigates the filtered velocity feedback(FVF) controller for the reduction of the acoustic power radiated from a clamped beam. The instability problem due to the non-collocated sensor/actuator configuration when using PZT actuator should be sorted out. The roll-off property of the FVF controller at high frequency helps to alleviate the instability. The dynamics of clamped beams under forces and moments pair and the FVF controller are first formulated. The formulation of the sound radiated power is followed. The open loop transfer function(OLTF) synthesized with 100 modes is used to determine the stability of the control system. The control performance is finally estimated. The levels of the vibration and the sound radiated power are reduced in the wide bandbelow the tuning mode of the FVF controller.

Sound Radiation Characteristics of Cracked Rectangular Vibrating Plates (균열을 갖는 직사각형 진동평판의 음향 방사특성)

  • 김태진;이우식
    • Proceedings of the KSR Conference
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    • 2002.10a
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    • pp.119-124
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    • 2002
  • This paper considers the sound radiation characteristics of a craked rectangular vibrating plate, varying the orientation angle of a line crack. The vibration response of the cracked vibrating plate is obtained by using ANSYS, the acoustic theory based on the lumped parameter model is used to calculate radiated sound power. The radiated sound powers are computed with varying the orientation angle of the crack: i.e, 0$^{\circ}$, 45$^{\circ}$, and 90$^{\circ}$. It is found that characteristics of the radiated sound power are very closely related to the crack orientation, vibration mode and crack location.

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Reduction of Sound Radiated Power of Clamped Beams using Filtered Velocity Feedback Controllers (Filtered Velocity Feedback 제어기를 이용한 양단지지보의 음향파워 저감)

  • Shin, Chang-Joo;Hong, Chin-Suk;Jeong, Wei-Bong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2011.10a
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    • pp.377-383
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    • 2011
  • This paper reports the filtered velocity feedback (FVF) controller to reduce the acoustic power from clamped beams. The instability problem due to the non-collocated sensor/actuator configuration when using PZT actuator should be resolved. The roll-off property of the FVF controller at high frequency helps to alleviate the instability. The dynamics of clamped beams under forces and moments pair and the FVF controller are first formulated. The formulation of the sound radiated power is followed. The open loop transfer function (OLTF) synthesized with 100 modes is used to determine the stability of the control system. The control performance is finally estimated. The levels of the vibration and the sound radiated power are reduced in the wide band below the tuning mode of the FVF controller.

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Sound Radiation Characteristics of A Cracked Rectangular Vibrating Plate (균열을 갖는 직사각형 진동평판의 음향 방사특성)

  • 김태진;박종환;이우식
    • Journal of the Korean Society for Railway
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    • v.6 no.3
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    • pp.163-168
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    • 2003
  • This paper considers the sound radiation characteristics of a cracked rectangular vibrating plate, varying the orientation angle of a line crack. The vibration response of the cracked vibrating plate is obtained by using ANSYS, the acoustic theory based on the lumped parameter model is used to calculate radiated sound power. The radiated sound powers are computed with varying the orientation angle of the crack: i.e, 0$^{\circ}$, 45$^{\circ}$, and 90$^{\circ}$. It is found that characteristics of the radiated sound power are very closely related to the crack orientation, vibration mode and crack location.

Effect of Offset of Bearing on Radiation Sound and Vibration in the Gear System (기어장치에서 베어링의 설치위치가 소음특성에 미치는 영향)

  • 류성기;이중희
    • Journal of the Korean Society of Safety
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    • v.13 no.1
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    • pp.34-39
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    • 1998
  • This paper describes a evaluation method of sound power radiated from the vibrating faces of a single stage gear box using sound radiation. The vibration caused from meshing gears is transmitted to the gear box faces through shafts and bearings. A Boundary Element Method (BEM) is developed to calculate the sound power radiated from the faces with their velocity response which is based on the Building Block Approach (BBA). Radiation efficiency as well as the sound intensity on the surface of the gear box is also calculated. Sound power of the gear box is larger in the case that bearings have offset to the wall of the gear box than that bearings are on the center of the gear box. The sound power increases with the augmentation of the offset.

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PREDICTION OF SOUND RADIATION FROM TIRE TREADBAND VIBRATION

  • Kim, B.S.
    • International Journal of Automotive Technology
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    • v.2 no.1
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    • pp.33-38
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    • 2001
  • The noise generated from a treadband mechanism of a tire has been the subject of this research. In particular, the treadband has been treated as an infinite tensioned beam resting on an elastic foundation which includes damping. The main objective is here to predict the sound power generated from a system mentioned above by locating harmonic point forces representing the excitation of treadband at the contact patch. It is possible to predict the sound power radiated from this structure by wavenumber transformation techniques. To find out the minimum radiated sound power, All parameters were varied. Thus this model can be used as a tire design guide for selecting parameters which produce the minimum noise radiation.

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Prediction of Radiated Sound on Structure-acoustic Coupled Plate by the Efficient Configuration of Structural Sensors (구조센서의 효율적인 구성을 통한 구조 음향연성 평판의 방사음 예측)

  • Lee, Ok-Dong;Oh, Jae-Eung
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.24 no.9
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    • pp.695-705
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    • 2014
  • In this paper, two types of techniques for the prediction of radiated sound pressure due to vibration of a structure are investigated. The prediction performance using wave-number sensing technique is compared to that of conventional prediction method, such as Rayleigh's integral method, for the prediction of far-field radiated sound pressure. For a coupled plate, wave-number components are predicted by the vibration response of plate and the prediction performance of far-field sound is verified. In addition, the applicability of distributed sensors that are not allowable to Rayleigh's integral method is considered and these can replace point sensors. Experimental implementation verified the prediction accuracy of far-field sound radiation by the wave-number sensing technique. Prediction results from the technique are as good as those of Rayleigh's integral method and with distributed sensors, more reduced computation time is expected. To predict the radiated sound by the efficient configuration of structural sensors, composed(synthesized) mode considering sound power contribution is determined and from this size and location of sensors are chosen. Four types of sensor configuration are suggested, simulated and compared.

A Quantitative Separation Method of Structure and Air Borne Sound Power from the Enclosure (차음구조물의 방사음향파워로부터 고체 및 공기전파음향파워의 정량적인 분리법)

  • 김의간;강동림
    • Journal of Advanced Marine Engineering and Technology
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    • v.16 no.5
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    • pp.85-96
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    • 1992
  • Engine enclosures are widely adopted to reduce the noise emission in various fields of application. The radiated noise, which is due to the vibration of enclosure's outer surface, is composed of two kinds of sound power with different path of propagation. One is the 'structure-borne sound power' which stems from the engine's vibratory force applied to the structure of enclosure through the mounting parts of engine etc., while the other is the 'air-borne sound power' which is originated by the sound power radiated from the engine surface to the inner space of enclosure that should excite the vibration of enclosure from inside. In order to get a most efficient engine enclosure is required a profound consideration upon the above structure-borne and air-borne noise, since the guiding principle of countermeasure for each noise is quite different. The controlling of input vibration and its isolation are major subject for the structure-borne sound power and the specifications of absorbing member and damping panels are the major interests for the air-borne sound power. Hence it seems very efficient to separate the total sound power into two categories with a great accuracy when one think of further reduction of engine noise from the exciting enclosure, however, its separating methods have not been made clear for many years. Then author proposes a new practical separation method of two propagation path's contribution to the total radiation sound power for the enclosure under the engine operating condition.

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The selection to position visco-elastic material for reduction radiated sound power from a stiffened plate (보강판의 음향방사파워저감을 위한 제진재의 위치선정)

  • 안호일;김사수
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1996.04a
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    • pp.257-262
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    • 1996
  • The first purpose of this study investigates the influence of stiffening on the acoustic response of stiffened plates, which are often employed in steel structures. And the radiation efficiency is measured by average mean square velocity and sound intensity of stiffened plates. The second, it determines influence of mass, damp and stiffeness due to the partial adhesive visco-elastic material to reduce radiated sound power.

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Placing Constrained Layer Damping Patches Using Reactive Shearing Structural Intensity in Order to Reduce the Radiated Sound Power of a Air-Conditioner Outdoor Unit (반동 전단 구조 인텐서티 측정에 의한 제진재 적용과 그에 따른 에어컨 실외기 구조 방사 소음 저감)

  • 김규식;강연준;진심원;정인화;이정우
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.333-337
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    • 2003
  • The use of reactive shearing structural intensity to place small patches of constrained layer damping material in order to achieve the largest reduction in the radiated sound power of Air-conditioner outdoor unit is described. The normal surface velocity of each panel was measured using a laser doppler vibrometer. Experimental results indicated that patches of constrained layer damping material placed over areas of high reactive structural intensity reduced the radiated sound power significantly more than patches of the same area placed over areas of low reactive structural intensity

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