Accurate characterisation of surface fatigue cracks (in steels) using the AC potential drop NDT technique

Abstract

In order to maintain the desired level of safety in an industrial environment, it is important that the structural integrity of all the components and equipment being utilised by the facilty is assured. To determine the structural integrity of an engineering system precisely, not only must the depth of the flaw be established, but the crack profile and orientation must also be obtained in order to assess the extent of the crack. The present work described in this thesis discusses the development of an AC potential drop (ACPD) system as a non-destructive testing (NDT) technique for flaw detection and sizing of variously shaped and oriented surface breaking fatigue cracks. The ACPD method was reviewed to establish its viability as an NDT technique, and to understand the response of the output to fatigue cracking. The proposed system using a mains power source with a frequency of 50Hz was investigated as a means of providing a sensitive and reliable measurement device that could be employed to analyse fatigue cracks in industrial components in situ.