Viscoelastic characterization of liquids using ultrasonic shear-waves generated by the internal reflection approach

Abstract

In this work, an implementation of the ultrasonic shear wave reflectometry technique for the viscoelastic characterization of liquids is reported. An alternative approach for shear wave generation was implemented. It employees a mode conversion inside a prism, avoiding the need for fluid delay lines. This approach provided shear waves without spurious echoes and good SNR in a wide frequency range. A measurement cell was implemented and its operation tested with glycerin and hydraulic oil samples. The cell allowed the determination of the complex shear modulus and viscosity in the frequency range of 0.36-6.1 MHz. The viscosity values calculated by two different methodologies led to deviations less than 16% in the case of glycerin and 40% in the case of Hydra-68, when compared to the values obtained with conventional viscometry. The experimental results showed that the viscoelastic behavior of the samples fitted well with the Kelvin-Voigt model.

Keywords: Internal reflection; Mode conversion; Shear wave reflectometry; Ultrasound; Viscoelasticity.