Analysis of fractional fourier transform for ultrasonic NDE Applications

In this study, a Fractional Fourier transform-based signal decomposition (FrFT-SD) algorithm is utilized to analyze ultrasonic signals for NDE applications. FrFT, as a transform tool, enables signal decomposition by rotating the signal with an optimal transform order. The search of optimal transform order is conducted by searching the highest kurtosis value of the signal in the transformed domain. Simulation study reveals the relationship among the kurtosis, the transform order of FrFT, and the chirp rate parameter. Furthermore, parameter estimation is applied to the decomposed components (i.e., chirplets) for echo characterization. Simulations and experimental results show that FrFT-SD not only reconstructs signal successfully, but also estimates parameters accurately. Therefore, FrFT-SD could be an effective tool for analysis of ultrasonic signals.