Crack length measurement: Analysis of the electropotential method using a finite element method

TLDR: In this paper, an evaluation of the electropotential method for deriving the crack length in a sheet metal specimen is carried out and compared with an existing analytical and numerical method for calculating the relationship between electropotor and crack length.

Abstract: An evaluation of the electropotential method for deriving the crack length in a sheet metal specimen is carried out. Comparisons are made between an existing analytical and numerical method for calculating the relationship between electropotential and crack length. The numerical method allows an exact representation of the specimen geometry which enables the influence of asymmetrical crack growth on the electropotential to be examined. A case study to analyse this effect on the electropotential is discussed which indicates that underestimation of the crack length will occur which becomes increasingly significant as the voltage probes across which the electropotential is measured are placed closer to the crack. The paper shows that a compromise must be made with regard to voltage probe positioning between the desired sensitivity of the potential reading and tolerated vulnerability to asymmetric crack growth. Comparisons between experimental and theoretical derived potential crack length relationshi...