Magnetostrictive strain sensor and method

Abstract

A magnetostrictive strain sensor () includes a magnetostrictive core () comprising a magnetostrictive material, such as a nickel-iron alloy, able to conduct a magnetic flux and whose permeability is alterable by application of a strain. A conductive coil () is proximate the magnetostrictive core () to generate the magnetic flux when electrically excited. A shell () surrounds the conductive coil () and the magnetostrictive core () for providing a conductive return path for the magnetic flux. An excitation source () is electrically connected to the conductive coil () for electrically exciting the conductive coil () with an alternating current having a constant magnitude. An in-phase voltage circuit () is electrically connected across the conductive coil (). The in-phase voltage circuit () senses an in-phase voltage that is in-phase with the alternating current. The in-phase voltage varies correspondingly to the strain subjected to the magnetostrictive core (). A processor () is operatively connected to the in-phase voltage circuit () to determine the strain applied to said magnetostrictive core () by comparing the in-phase voltage to a predetermined relationship between strain and in-phase voltage.