Impact-Echo Non-Destructive Testing and Evaluation with Time-Frequency Data Process and Analysis

Mark Emde and Ruichong Zhang


Linear and Nonlinear Time Series Analysis, Impact-Echo, Hilbert-Huang Transform with Ensemble Empirical Mode Decomposition, Non-Destructive Testing and Evaluation


Impact-echo testing is a form of non-destructive testing and evaluation, which utilizes wave propagation to find mechanical properties of a material, such as concrete or masonry. One of the largest issues faced with impact-echo testing is the time-frequency analysis for calculating the correct resonant frequency, which allows the thickness of the material or depth of a crack to be calculated. It has been found that the current frequency analysis method, i.e., Fourier spectral analysis, cannot accurately calculate the resonant frequency, without the need for correction factors. Even with the adjustment of correction factors, it is found that Fourier analysis still involves errors in the estimation of thickness. A new time-frequency analysis method, the Hilbert-Huang Transform (HHT) with Ensemble Empirical Mode Decomposition (EEMD), utilizes the characteristic time scale and white noise to find the instantaneous frequency and amplitude. This method allows an improved precise answer to be found, without the need for correction factors. This study examines research that utilizes the HHT with EEMD as a time-frequency data process for the analysis of impact-echo testing data. Results show that HHT with EEMD is more accurate than current data analysis methods, but further research is needed to verify results.

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