Ultrasonic testing is used to detect and classify flaws on aerospace structures using signal processing techniques. Flaw
diagnosis algorithms have been developed on actual aircraft structures using the raw data. Time domain and Fourier analysis
is being carried out and then their shortcomings are addressed using time frequency analysis, due to non stationary nature of
ultrasonic acquired signal from Aerospace structures. Hilbert Huang Transform is then applied to observe and characterize
flaws. Effect of frequency modes and energy distribution on particular locations is examined in this research to detect and
analyze Region of Interest for diagnosis and subsequent crack estimation.
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