NEW MAGNETOELASTIC FORCE SENSOR USING AMORPHOUS-ALLOYS

Most amorphous alloys combine good mechanical properties with appropriate magnetic properties. They possess a high permeability as well as a large range of elastic strain with very small elastic hysteresis. Due to their magnetoelastic properties, some amorphous alloys can be used as force-sensing materials. This work deals with sensors for tensile forces using only one single ribbon of an amorphous alloy. In contrast to conventional strain gauges, these ribbons are strong enough to serve as the load-bearing component, which avoids fixing the sensor element to another elastic material. Using the usual arrangement of coaxial coils for transmitting and receiving, the maximum permeability, the remanence, the coercive force and the magnetic losses have been studied as functions of the applied force for three different materials (Fe70 Ni8 Si10 B12, Ni39 Fe39 Mo4 Si6 B12 and Co75 Si15 B10). In addition, a very promising novel sensor principle has been found by providing the individual thin ribbons with a modified arrangement of solenoidal coils. In this case a seeming change of the saturation magnetization is a suitable and sensitive measuring signal. © 1990.