Detection of surface cracks in metals using time-domain microwave non-destructive testing technique

This study theoretically investigates the application of ultra-wideband (UWB) signals in crack detection as a microwave non-destructive testing technique which is well developed in frequency domain in recent decades. To analyse UWB signals, with traditional frequency-domain methods, is needed to cover a wide range of separate frequencies. Another approach is to solve the problem with time-domain (TD) techniques in which fields are assumed as general functions of time instead of single frequency harmonics. The advantages of such TD numerical techniques are first, their applicability for arbitrarily wide-frequency range by one-time execution, and second that they give the potential for detection of small changes in the received signal that corresponds to small but sometimes significant defects of specimen. As it will be shown, using UWB pulses is an efficient way for detection of fine cracks which are of practical importance.