Sensitivity of the second resonance mode of a near-field acoustic sensor to viscoelastic media: Investigation of bitumens

The alterations of the resonance frequency of the vibrating tip of an acous tic sensor detect the density and the viscosity of liquids. The employed ac oustic near-field sensor has several resonance frequencies which correspond to its different parts. We determined that the resonance of the body of th e acoustic sensor is sensitive to the rheological characteristics of viscoe lastic media. We carried out experiments with bitumens and we modified the acoustic load on the sensor in two ways: the immersion depth of the tip and the temperature of the bitumen specimens. Theoretical and experimental res ults are compared.