Abstract
The feasibility of the use of ultrasonic thermometry for in-situ monitoring of temperature rise in friction surface has been examined. The ultrasonic thermometry that is a method providing internal temperature measurements by ultrasound has been applied to temperature measurements of a heated material by friction and an attempt to monitor transient variations in temperature profile near friction surface as well as the surface temperature during friction process has been made. The temperature profiles including the friction surface temperature are quantitatively determined by a combined method consisting of ultrasonic pulse-echo measurements and a finite difference calculation for estimating one-dimensional temperature distributions along the direction of ultrasound propagation. To demonstrate the practical feasibility of the method, the ultrasonic pulse echo measurements at 2 MHz are performed for an acrylic resin plate of 10 mm thickness whose single side is being rubbed with a felted fabric. The temperature at the friction surface and internal temperature distribution of the acrylic resin plate are measured during the rubbing process and the transient variations of the measured temperatures are obtained. Quick temperature rise of approximately 80 K at the friction surface is observed within 10 s after the rubbing starts. It is noted that the temperatures measured by the ultrasonic method almost agree with those measured using thermocouples inserted into the acrylic resin plate. Thus, in-situ measurement of interfacial temperature in frictional surface by the ultrasonic thermometry has been demonstrated.
