ESTIMATION OF ERROR IN MEASURING THE DEPTH OF SURFACE CRACKS BY THE ELECTROPOTENTIAL METHOD ON AN ALTERNATING CURRENT

Abstract

The study carried out research on the error in measuring the depth of surface cracks by the electropotential method on an alternating current with a variation in the magnetic permeability and specific electrical conductivity of the metal. The measuring error appear from the difference between the electromagnetic properties of the metal of the sample used to obtain the calibration dependences and the properties of the metal of the tested object. The research conducted by the method of the finite element. The analysis of the dependences of the electropotential signal in the frequency range for the defect-free area and the area with a surface crack is carried out. The study of the error in measuring the depth h, that depends on the frequency of the transmitted current and the value of h. The comparison of the errors arising from various methods of choosing the calibration characteristics is performed, including the comparison of the equality of electropotential signals in the defect-free areas of the tested area and the test sample selected for calibration.