Determination of stress in ferromagnetic steel by potential drop measurements

Abstract

A technique has been investigated in which absolute stress inferromagnetic materials can be determined by measurements of the response to injected current steps in parallel with the stress direction. Pairs of transient potential drop response signals, measured under various bias magnetic conditions, are the basis for calculating a parameter representing the stress in the material. Calibration curves, involving the above mentioned parameter as a function of stress, are very close to being linear, at least in the tested range of — 200 MPa (compression) to 250 MPa (tension). The observations in the described experimental work can to some extent be explained by the theory on the relationship between stress and magnetic properties. Further investigations related to the problem of the determination of stress in railway rails are planned.