Magneto-elastic Strain Sensors for Use on Steel Rods

This work describes a magneto-elastic strain sensor based on the.E effect and discusses some of the materials used in its construction. A polycrystalline FeAlB alloy with a magnetostriction around 80 ppm was used as the transducer and was glued to the test object, in this case, rods of SAE 1010 steel. The magnetic field of the transducer modified the operating point of the resonator, a strip of field-annealed Metglas 2826MB3, resulting in a modification of its resonant frequency. For a sensor with resonant frequency of 60.5 kHz, a total resonant frequency variation Delta f similar to 7 kHz was observed for a deformation of 1100 ppm. We conclude that the wireless monitoring of a steel surface would be possible with this device.