Ultrasonic Monitoring of Internal Temperature Distribution in a Heated Material

An ultrasonic method for internal temperature monitoring is presented. The principle of the method is based on the temperature dependence of ultrasonic velocity in materials. An inverse analysis to determine the one-dimensional temperature gradient in a heated plate is developed and an experiment is carried out to verify the validity of the developed method. A single side of a silicone rubber plate of 30 mm thickness is heated and ultrasonic pulse–echo measurements are then performed during heating. A change in the transit time of ultrasonic waves in the heated rubber is monitored and used to determine the transient variation in the internal temperature gradient of the rubber. The internal temperature gradient determined ultrasonically agrees well with both results obtained using commercial thermocouples installed in the rubber and estimated theoretically.