Tutorial. Signal processing aspects of structural impact testing

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    Abstract

    Spectra estimated from structural impulse tests via fast Fourier transform (FFT) algorithms are susceptible to data acquisition related difficulties. The problem stems from vibration response signals which decay sufficiently slow that it is impractical to capture the waveform in its entirety. The problem is further compounded by the data acquisition and processing constraints imposed by FFT equipment. This paper reviews and investigates various aspects of FFT based signal processing in relation to commonly encountered situations in structural impact testing. The analysis is based on time and spectral relationships developed for a single degree-of-freedom (SDOF) system excited by a half sine force impulse. The truncation problem is investigated and the results show that provided at least six time constants of data are captured the error in the estimated frequency response function magnitude and phase is less than 0.5%. Next, the coloring effects of exponential windowing on spectra from an idealized impact test are examined. The results indicate that the windowing effects can be usually compensated for and accurate modal parameters extracted. Finally, the 'double hit' phenomena is examined to illustrate the effects on the spectra and the implications with respect to modal analysis procedures.

    Original languageEnglish (US)
    Pages (from-to)129-149
    Number of pages21
    JournalThe International journal of analytical and experimental modal analysis
    Volume7
    Issue number2
    StatePublished - Apr 1992

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    Impact testing
    Fast Fourier transforms
    Signal processing
    Data acquisition
    Coloring
    Modal analysis
    Frequency response

    All Science Journal Classification (ASJC) codes

    • Engineering(all)

    Cite this

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    title = "Tutorial. Signal processing aspects of structural impact testing",
    abstract = "Spectra estimated from structural impulse tests via fast Fourier transform (FFT) algorithms are susceptible to data acquisition related difficulties. The problem stems from vibration response signals which decay sufficiently slow that it is impractical to capture the waveform in its entirety. The problem is further compounded by the data acquisition and processing constraints imposed by FFT equipment. This paper reviews and investigates various aspects of FFT based signal processing in relation to commonly encountered situations in structural impact testing. The analysis is based on time and spectral relationships developed for a single degree-of-freedom (SDOF) system excited by a half sine force impulse. The truncation problem is investigated and the results show that provided at least six time constants of data are captured the error in the estimated frequency response function magnitude and phase is less than 0.5{\%}. Next, the coloring effects of exponential windowing on spectra from an idealized impact test are examined. The results indicate that the windowing effects can be usually compensated for and accurate modal parameters extracted. Finally, the 'double hit' phenomena is examined to illustrate the effects on the spectra and the implications with respect to modal analysis procedures.",
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    Tutorial. Signal processing aspects of structural impact testing. / Trethewey, Martin Wesley; Cafeo, J. A.

    In: The International journal of analytical and experimental modal analysis, Vol. 7, No. 2, 04.1992, p. 129-149.

    Research output: Contribution to journalArticle

    TY - JOUR

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    AU - Trethewey, Martin Wesley

    AU - Cafeo, J. A.

    PY - 1992/4

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