LAUSR

We present an experimental work in which the magnetoelastic resonance is used to determine the viscosity of lubricant oils in a wide range of values. Two different amorphous ribbons, clamped by one end, are immersed in oils with viscosities ranging from 32 to 320 cSt. The magnetoelastic resonance curve corresponding to the first longitudinal oscillation mode is measured inductively. An analysis method based in a least-squares fitting to a simple phenomenological expression, derived from the linear response formalism, allows determining the main parameters characterizing the resonance as a function of the oil viscosity. Both the frequency and the amplitude of the resonance show a strong dependence on the viscosity, but importantly, our analysis method additionally determines the dependence of the damping parameter, which is intrinsically dependent on the viscosity of the surrounding medium. We demonstrate that the analysis procedure is capable of analyzing a complex case in which two oscillation modes are excited simultaneously. We show that, in this case, the oils with larger viscosity produce a preferential damping of the higher frequency mode.