The use of ac field measurement technique in crack profile prediction

Abstract

The depths of surface cracks of different profiles have been estimated using the alternating current field measurement technique. The method made use of an instrument known as Crack MiCroGauge. From the results, it was found that the technique produced reasonably good accuracy for cracks of constant depth particularly at the central region of the crack. Underestimation of the crack depth by about 20–35% was generally observed for cracks of semi-elliptical and irregular profiles. However, with an absolute accuracy of about 2 – 3 mm in the measurement of cracks of lengths ranging from 30 – 80 mm and depths from about 2 – 30 mm, the technique is believed to be comparable in accuracy to other commonly employed nondestructive testing techniques. The present technique may indeed have advantages over its counterparts in its simplicity of use.