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A new application of a high sensitivity magnetoelastic resonator able to measure period and damping constant of low frequency torsional oscillation is described and validated by experimental tests. The sensitive parameter is the amplitude of resonant magnetoelastic waves in the soft ferromagnetic core (Fe 62.5 Co 6 Ni 7.5 Zr 6 Cu 1 Nb 2 B 15 amorphous ribbon). The theoretical model of the device has been developed, correlating torsional oscillations to the friction force applied by the fluid in which they occur. Thus, an accurate indirect evaluation of fluid viscosity has been demonstrated. The main prerogative of the proposed sensor is to work without contact with the oscillating mechanism. As experimental validation, viscosity of UHT milk was measured versus different fat content. The experimental comparison with a standard rheometer demonstrates the new device competitiveness in the measure of low viscosity fluids at low share rate. Moreover, the detected behaviors at increasing temperature are in agreement with previous literature. In perspective, the new magnetoelastic resonators application can be very ductile and effective in on-line monitoring of viscosity change with time to control composition, degradation or contamination of liquids.

The development of a versatile magnetoelastic sensor prototype for on-line elastic deformation monitoring and fracture alarm in civil engineering is reported. The sensor is based on the variation of resonant longitudinal magnetoelastic waves amplitude due to elastic status change in the amorphous Fe62.5Co6Ni7.5Zr6Cu1Nb2B15 active core. Tests on a tufa wall under mass loading were conducted. The obtained results show a good reliability and sensitivity (1mV/10 mu m) of the sensor response in the mu m-cm deformation range. The sensor is able to predict the approaching to the fracture regime, monitoring a preceding characteristic behavior. (c) 2005 Elsevier B.V. All rights reserved.

The development of a novel magnetoelastic sensor, based on the stress influence on amplitude of the resonant mechanical waves inside a Fe 62.5 Co 6 Ni 7.5 Zr 6 Cu 1 Nb 2 B 15 ribbon, for strain and/or stress real-time monitoring in civil buildings is reported. This novel sensor exhibits better sensitivity than resistive and vibrating wire strain gauges, good reliability and stability.