Comparisons of AC Magnetostriction of Non-Oriented Electrical Steels Measured in Epstein and Disc Samples

Magnetostriction data of non-oriented electrical steel is needed for calculation of deformation and vibration of electrical machine cores. It is characterised on various sample shapes using several measurement techniques which may give different results. In this paper, measurement results of AC magnetostriction of two commercial non-oriented steels magnetised at angles to the rolling direction in standard Epstein strip and disc samples are presented. Magnetostriction measured in disc samples magnetised in a twodimensional magnetisation system revealed that the highest magnetostriction in the sheet plane may not occur along the magnetisation direction if the material is anisotropic. Sample geometry also caused differences of magnetostriction measured in the Epstein and disc samples due to the form effect. The results show that magnetostriction measured in Epstein strip form should be used with caution for calculation of core deformation and vibration of large electrical machines