Application of Fiber Bragg Grating to Determine the Terfenol-D Magnetostriction Characteristics for Sensor Development

The magnetic bodies present deformation in the direction of the magnetic field and this phenomenon is called magnetostriction. Electric current sensors based on magnetostriction have been reported in several papers. In common these previous papers use i¬ber Bragg grating (FBG) to perform the direct measurement of strain caused by the magnetostrictive material. However, magnetostriction sensors present few disadvantages often neglected, such as the temperature dependence. In this paper a Terfenol-D rod (a giant magnetostrictive material-GMM) is used as well as two multiplexed FBGs for simultaneous strain and temperature measurement. One of them is encapsulated in an alumina tube and it is subjected to temperature variation. The i¬rst result presents unipolar characteristics of Terfenol-D magnetostriction. Other experiments determine the Terfenol-D response for different temperatures. The Terfenol-D sensitivity increases when the temperature increases, however the saturation of the material occurs for small i¬eld values. The issues presented in this paper must be taken into account on the development of magnetostrictive sensors.