Evaluation of size, shape and location of a semi-elliptical surface crack using direct current electrical potential method

摘要

A method was proposed for non-destructive evaluation of the size and location of a semi-elliptical crack on the surface of a plate specimen using a direct current electrical potential method (DC-EPM). Three pairs of probes were attached (orspot-welded) to the specimen around the crack, and the potential difference was measured at these points. A combination of the length, depth and location of a crack, which gave the nearest potential difference to the measured value, was regarded as thesolution. Calculation of the potential difference between each pair of probes was efficiently carried out using an approximated solution presented by the authors. After the validity of the method was examined using the solution by finite element method,the technique was applied to an actual fatigue crack in a plate specimen of steel and it was found to have successfully evaluated the length and depth of the crack.