Accession Number:

ADA289776

Title:

Spectral Analysis Techniques Using Wavelets as an Alternative to Fourier Analysis for Transient Dynamic Data

Descriptive Note:

Final rept. Oct 1993-Sep 1994

Corporate Author:

ARNOLD ENGINEERING DEVELOPMENT CENTER ARNOLD AFB TN

Report Date:

1995-01-01

Pagination or Media Count:

65.0

Abstract:

Various dynamic data analysis tools for one-dimensional time-domain signals are employed to determine the frequency content of a signal for mechanical analysis. When tied to the fundamental frequency of the various components comprising the machinery being evaluated, this information gives an indication of the state or health of the machine. Current techniques for evaluating dynamic data for potential mechanical problems are primarily centered around the Fast Fourier Transform FFT and the Shon Time Fourier Transform STFT. However, the use of Fourier analysis for frequency component extraction is restricted to bandlimited stationary signals. Because of the stationary requirement, small transients may not be detected due to a smoothing effect of the FFT, or the FFT spectrum may be smeared due to frequency ramping and abrupt incidents or discontinuities in the signal. Various techniques have been employed to overcome the limitations of the FFT for non-stationary data. These techniques include windowed Fourier analysis including the STFT and a background in wavelet theory based upon the analyzing function basis approach so that wavelet theory may be contrasted against Fourier analysis. A model signal with stationary and transient characteristics is developed to permit comparisons of various analysis techniques based upon a known analytic signal which resembles a real vibration signal. Some applications of wavelets to other transient signals are also provided.

Subject Categories:

  • Operations Research
  • Mechanics
  • Machinery and Tools

Distribution Statement:

APPROVED FOR PUBLIC RELEASE