The effect of strain on the a.c. resistance of a metal: a method of studying microplasticity

Abstract

The effective a.c. resistance of a conductor is a function of the frequency of the current and the resistivity and the permeability of the conductor. The resistivity and permeability are affected by strain and, by using a suitable high-frequency a.c. bridge, these effects can be amplified and measured as a function of strain. In this paper it is shown that the changes in the effective a.c. resistance which result from straining a ferromagnetic metal can be used as a method for determining the onset of plasticity and, more important, that of microplasticity, which occurs while the material is in the nominally elastic region.