Time-of-flight diffraction (TOFD) technique for accurate sizing of surface-breaking cracks

This paper deals with an experimental study for evaluation of TOFD technique for determination of size of the surface-breaking cracks. It extends the results presented in a previous paper((1)). The study was confined to simulated cracks (machined slits). Difficulty was experienced using TOFD to size simulated cracks extending less than about 2 mm depth. This is due to the presence of the lateral wave, which obscures the tip-diffracted signals from the simulated cracks close to the surface and also due to the inherent lack of time resolution near the surface. Experimental errors are presented.