Measurement of dynamic magnetostriction under rotating magnetic field

Rotational dynamic magnetostriction was measured as a function of rotating magnetic flux density on nonoriented and grain-oriented silicon steel sheets under various magnetization conditions. Rotational dynamic magnetostriction was measured by using a special strain gage which provides x- and y-direction output. Rotational magnetostriction is shown to be considerably larger than conventional alternating magnetostriction along the rolling direction because rotational dynamic magnetostriction is generated by the appearance and disappearance of 90 degrees magnetic domain walls under the rotating flux density. The results obtained explain why the cores of rotating machines and three-phase transformers show larger magnetostriction than that predicted by rolling direction measurements of single-strip sheets under alternating flux.>