• Title/Summary/Keyword: ODS(Operational Deflection Shape)

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Application of curvature of residual operational deflection shape (R-ODS) for multiple-crack detection in structures

  • Asnaashari, Erfan;Sinha, Jyoti K.
    • Structural Monitoring and Maintenance
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    • v.1 no.3
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    • pp.309-322
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    • 2014
  • Detection of fatigue cracks at an early stage of their development is important in structural health monitoring. The breathing of cracks in a structure generates higher harmonic components of the exciting frequency in the frequency spectrum. Previously, the residual operational deflection shape (R-ODS) method was successfully applied to beams with a single crack. The method is based on the ODSs at the exciting frequency and its higher harmonic components which consider both amplitude and phase information of responses to map the deflection pattern of structures. Although the R-ODS method shows the location of a single crack clearly, its identification for the location of multiple cracks in a structure is not always obvious. Therefore, an improvement to the R-ODS method is presented here to make the identification process distinct for the beams with multiple cracks. Numerical and experimental examples are utilised to investigate the effectiveness of the improved method.

A Study on Transfer Characteristics of Vehicle Air-conditioner Booming noise (차량용 에어컨 부밍 소음의 전달 특성에 관한 연구)

  • Lim, Seung Taek;Joo, Kyung Hoon;Ahn, Hew Nam;Park, Young Duk;Kang, Yean Jun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2013.04a
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    • pp.476-481
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    • 2013
  • Transfer path analysis(TPA) and operational deflection shape(ODS) have been widely utilized to analyze the characteristics of noise. TPA enables to decompose a noise into air-borne and structure-borne noises then estimate the path contribution of noise. ODS enables to analyze a moving shape and direction of interest components at a particular frequency. In this paper, TPA and ODS are applied to transfer paths of air-conditioner booming noise in a vehicle to reduce noise level, then a fixture is mounted it's path for distributing the high portion path contribution to the low portion path contribution. Through this experiment, the reduction of sound pressure level in air-conditioner booming noise is observed. Thereafter, TPA is again employed to verify the results of contribution.

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Noise, vibration Characteristic Identification and Noise Control of Indoor Air-Conditioner's Cabinet using Operational Deflection Shape (운행 중 변형형상을 이용한 에어컨 실내기 캐비닛의 소음/진동 특성 파악 및 제어)

  • Lee, Seong-Jin;Oh, Jae-Eung;Lee, Jung-Youn;Kang, Tae-Ho
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.830-833
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    • 2004
  • An indoor package air-conditioner (PAC) has complex noise sources such as motor noise and fluid noise caused by the fan motor, heat transfer and shroud. Sound intensity techniques and ODS(Operational deflection shape) techniques are applied to identify the noise characteristics of an indoor air-conditioner's cabinet. The sound intensity is used to visualize the noise source locations. and the ODS to visualize the vibration pattern and to obtain the dynamic characteristics of the noise source. Acoustic intensity and operational deflection distribution are obtained in space domains as well as frequency domains. Using the visual information of source locations and its dynamic characteristics, the damping patch is applied to reduce structure borne noise in the cabinet. As a result, the noise emitted by the cabinet is reduced by 5dB.

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Operation Deflection Shapes Analysis for Vibration Reduction of ATM Case (ODS 해석에 의한 ATM 케이스 진동 저감)

  • Shin, Bum-Sik;Lee, Seung-Mock;Kim, Do-Hyun;Choi, Yeon-Sun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.232-237
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    • 2006
  • Operation deflection shapes(ODS) is defined as a motion of structure at particular frequency. The ODS is eligible to show any types of structural motions while the modes supply solutions only to linear and stationary motion. The principal vibration source of an auto teller machine(ATM) case was occurred due to resonance which was found by modal analysis. To reduce the vibration of ATM case, the motion of the case was visualized using ODS analysis, which can suggest how to modify the structure. As a result the vibration of the ATM case was greatly reduced with a stiffening bar between the opposite plates.

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Noise Reduce in the Rotary Compressor for air-conditioner using Structural Modification (구조 변경을 통한 공조용 압축기의 소음저감)

  • Kim, Jin-Soo;Lee, Seung-Mock;Ha, Jong-Hun;Lee, Jang-Woo;Ha, Sam-Chul
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2010.10a
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    • pp.556-563
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    • 2010
  • The main noise source of the rotary compressor for air conditioner was analyzed by using the measurement of sound intensity, modal analysis and operational deflection shape(ODS) analysis. In this study, the key noise source of rotary compressor was an accumulator, and noise was sharply increased due to the accumulator's resonance which has a big contribution to the noise. To reduce the excessive noise generated from accumulator, structural modification through ODS analysis were applied. Its validation was conducted by the measurement of noise and vibration on the accumulator's surface. The total noise was significantly reduced by 4.2dB(A).

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Structural and Sound Field Analysis of the High Speed CD-ROM Disk Drive (고속 CD-ROM Drive의 구조 및 음장 해석)

  • Yim, Woong-Sub;Cha, Sung-Woon;Lee, Jae-Seung;Moon, Yong-Rak
    • Proceedings of the KSME Conference
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    • 2001.06b
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    • pp.210-215
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    • 2001
  • CD-ROM Drives Rotating high speed as 10000 rpm cause serious noise and vibration problems. At the high speed, dominant noise is Air Borne Noise produced from high-speed airflow and Structure Borne Noise produced from structural vibration. In this research, vibration and sound characteristics in CD-ROM Drive were studied by the use of experimental analysis and computational simulation. Sound intensity techniques and ODS(Operational Deflection Shape) techniques are applied to identify the acoustic noise source of CD-ROM drive. And Computational simulation using SYSNOISE is conducted for describing the noise behavior.

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Vibration Reduction of Walking-type Cultivator's Handle using Modal Analysis and Operational Deflection Shapes Techniques (모드 해석과 운전 중 변형 형상 기법을 이용한 보행형 관리기의 핸들 진동 감소 방안)

  • 박영준;이윤세;김경욱
    • Journal of Biosystems Engineering
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    • v.29 no.2
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    • pp.101-108
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    • 2004
  • The objectives of this study were to determine the natural frequency of a walking-type cultivator's handle using a modal analysis, to determine whether or not the handle resonates with forcing frequency induced by its engine, and to determine a method to reduce the handle vibration using a technique of the operational deflection shapes(ODS). Results of the study are as follows: The natural frequencies of the handle up to third harmonics were found to be 20.4, 22.5 and 92.1 Hz in the vertical direction and 14.9, 93, and 132 Hz in the horizontal direction. It was found that the handle does not resonate with the forcing frequency of the engine, which is 52 Hz. The operational deflection shape analysis revealed the deflected shapes of the handle in the vertical and horizontal directions and suggested that the handle vibration can be reduced by adding some mass to the place where the largest deflection occurs. Attaching of 1.1 kg mass adjacent to the largely deflected area resulted in reductions of vibration from 9.45 to 8.03 m/s$^2$ in x-axis direction from 3.89 to 3.16 m/s$^2$ in y-axis direction and from 7.89 to 3.09 m/s$^2$ in z-axis direction, which are respectively 15, 19 and 61% reductions. The total vibration level was reduced by 29%, indicating that mass-adding method by the ODS is very effective for reducing the handle vibrations of the cultivators.

Beat Map Drawing Method for a Large Size Bell using ODS (ODS를 이용한 대형종의 맥놀이 지도 작성법)

  • Park, In-Seok;Lee, Jung-Hyeok;Park, Sun-Mi;Kim, Seock-Hyun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2012.04a
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    • pp.929-932
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    • 2012
  • Beat map shows the distribution property of the beating sound in the bell structure. Using the beat map, beat control and beat estimation are available. To draw the beat map, mode pair parameters of the bell are required. However, in case of large bell which is struck by a heavy wooden hammer, it is very difficult to measure the excitation force and to obtain the mode pair parameters. In this paper, we determined the mode pair parameters of the bell from the transmissibility between the roving signal and reference signal, using ODS(operational deflection shape) method. The mode pair data are input to the theoretical model of the beat response and beating waves are generated on the bell circumference. All the numerical and beat map drawing procedures are automatized using Matlab. Finally, the reliability of the beat map generated by the program is verified.

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Noise Reduction Design of Plasma Display Panel (플라즈마 디스플레이의 저소음 설계)

  • Park, Dae-Kyong;Kweon, Hae-Sub;Jang, Dong-Seob
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.11a
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    • pp.369.2-369
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    • 2002
  • For the evaluation of the plasma display panel (PDP)'s noise, vibration and sound characteristics of fanless PDP are measured and investigated. PDP is a type of two-electrode vacuum tube which operatres on the same principle as a household fluorescent light. An inert gas such as argon or neon is injected between two glass plates on which transparent electrodes have been formed, and the glass is illuminated by generating discharge. (omitted)

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