Depth measurement of notches as models for shallow cracks in concrete

The objective of this research is to investigate how the stress wave propagation is affected by the various shallow notches when time-of-flight diffraction technique is utilized to measure the depth. Numerical and experimental tests were carried out on a specimen containing notches, from 10 to 100 mm in depth. Results show that if the pulse shape of initial disturbance is downward, notch depth is larger than the instrument configuration distance and the depth can be measured accurately by the recorded transit time. The upward initial disturbances also reveal that the notch depth is less than the instrument configuration distance.