Flaw detection in metals by the ACPD technique: Theory and experiments

The Alternating Crack Potential Drop (ACPD) technique is mainly used to characterize surface cracks in metals. To-date, this technique has the following two limitations: it is limited to the so-called thin skin assumptions, and is applicable to open (visible) flaws. Saguy and Rittel recently proposed a methodology based on numerical simulations to overcome these limitations [Saguy H, Rittel D. Bridiging thin and thick skin solutions for alternating currents in crack conductors. Appl Phys Lett J 2005; 87: 84103–84103/3; Saguy H, Rittel D. Alternating current flow in internally flawed conductors: a tomographic analysis. Appl Phys Lett J 2006; 89: 94102–94102/3]. This paper presents experimental results, which support the proposed solutions and methodology to expand the universality of the ACPD technique as a key NDT tool.