Ultrasonic Instrumentation for Simultaneous Rheological and Ultrasonic Measurements on a Rheometer

The purpose of this work is to develop an ultrasonic instrumentation adapted to parallel plate rheometer (MCR302). This implementation enables simultaneous ultrasonic and rheological measurements to correlate ultrasonic velocity with the viscosity of tested materials as a function of temperature. Time of flight (TOF) measurement from the signal propagating in the material and reflected by the upper rheometer metallic plate allows to determine the acoustic velocity in situ in the rheometer. This method has first been validated and compared with measurements performed by a classical transmission method at 25°C on 3 silicone oils with different calibrated viscosities (10
³
, 10
⁴
, and 10
⁵
cSt). These measurements have then been extended by varying the silicone oil temperature in the 25-85°C range, allowing to compare velocity and viscosity measurements during a temperature rise.