Determination of frequencies from fringe patterns using short-term Fourier transforms and wavelet transforms.

摘要

In this research, space-frequency localizations were applied to moiré fringe patterns to analyze strain distributions. Short-time Fourier transform, Wigner-Ville distribution and wavelet transform are applied to moire fringe pattern analysis. Wavelet transform proved to be a very powerful tool for frequency analysis when compared with other methods. This theory is similar to short-time Fourier transform, but it has multiresolution framework for space-frequency localization. This method overcomes some disadvantage of short-time Fourier transforms.; The space-frequency localizations for measuring strains have been developed. Techniques for analyzing and measuring moiré fringes patterns, and the necessary algorithms have also been developed. The system has been successfully employed for the direct measurement of strains from the moiré fringe patterns.