• Title/Summary/Keyword: CSLDV

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Mode Shape Reconstruction of an impulse excited structure using HHT and CSLDV (HHT와 연속스캐닝 진동계를 이용한 임펄스가진된 구조물의 모드 형상 복원)

  • Kyong, Yong-Soo;Kim, Dae-Sung;Dayou, Jedol;Park, Kyi-Hwan;Wang, Se-Myung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.04a
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    • pp.484-490
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    • 2008
  • For CSLDV, the Chebyshev demodulation (or polynomial) technique and Hilbert transform approach have been used for mode shape reconstruction with harmonic excitation. In this paper, the Hilbert-Huang transform approach was applied as an alternative to impact excitation cases in terms of a numerical approach. The vibration of the tested structure is modeled using impulse response functions. In order to verify this technique, a simply supported beam was chosen as the test rig. With additional innovative steps which are the ideal-band pass filter and the nodal point determination, Hilbert-Huang transformation can be used for a good mode shape reconstruction even in the impact excitation case.

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A Continuous Scanning Laser Doppler Vibrometer for Mode Shape Analysis (모드형상분석을 위한 연속 스캐닝 레이저 도플러 진동측정기)

  • 라종필;최지은;박기환;경용수;왕세명;김경석
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.05a
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    • pp.274-280
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    • 2002
  • This paper addresses the vibration mode shape measurement technique utilizing a Continuous Scanning Laser Doppler Vibrometer (CSLDV). The continuous scanning capability is added to the conventional discrete Laser Doppler Vibrometer by reflecting the laser beams on the surface of the object using two oscillating mirrors. The bow scanning resulted from the proposed scanning method is eliminated by feedback control. The velocity output signal from the CSLDV is modulated to give the spatial velocity distribution in terms of coefficients which are obtained from the Fast Fourier Transformation of the time dependent velocity signal. Using the Chebyshev series form, the analysis of the vibration mode shape techniques for straight Bine scanning and 2 dimensional scanning are presented and discussed. The performance of the proposed SLDV is presented using the experimental results of the vibration mode shape of a plate

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A Continuous Scanning Laser Doppler Vibrometer for Mode Shape Analysis (모드형상분석을 위한 연속 스캐닝 레이저 도플러 진동측정기)

  • Park, Kyi-Hwan;Choi, Ji-Eun;La, Jong-Pil;Wang, Sem-Yung;Kyoung, Yong-Soo;Kim, Koung-Suk
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.5
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    • pp.734-741
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    • 2003
  • This paper addresses the vibration mode shape Measurement technique utilizing a Continuous Scanning Laser Doppler Vibrometer (CSLDV). The continuous scanning capability is added to the conventional discrete Laser Doppler Vibrometer by reflecting the laser beams on the surface of the object using two oscillating mirrors. The bow scanning resulted from the proposed scanning method is eliminated by feedback control. The velocity output signal from the CSLDV is modulated to give the spatial velocity distribution in terms of coefficients which are obtained from the Fast Fourier Transformation of the time dependent velocity signal. Using the Chebyshev series from, the analysis of the vibration mode shape techniques for straight line scanning and 2 dimensional scanning are presented and discussed. The performance of the proposed SLDV is presented using the experimental results of the vibration mode shape of a cantilever and plate

Investigation about unexpected effects of Chebyshev and Hilbert approach on using CSLDV (연속 스캐닝 진동계를 위한 체비세프와 힐버트 방식의 비교)

  • 왕세명;경용수;박기환;라종필;김경석;강기수;김창식
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.05a
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    • pp.414-419
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    • 2003
  • There are some methods fur extracting mode shapes from a continuously scanned data such as a modulation, Chebyshev polynomial, and Hilbert approach. In this paper, Chebyshev and Hilbert approaches were investigated through the numerical experiment first. As some experimental parameters were altered with small quantities, data were checked and plotted. From those results, the effects of unexpected parameters will be configured. And then, it will be actually helpful to select the proper method for specific testing environments.

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