Electroacoustic method for nondestructively monitoring the internal temperature of objects

Abstract

A method for nondestructively monitoring the internal temperature of objects having poor thermal conductance, such as tires, includes the initial steps of determining the internal temperature of a reference object or a representative portion thereof at a plurality of internal temperatures (T), measuring a plurality of pulse propogation times (t T ) taken by an ultrasonic frequency pulse signal to propogate through the reference object or a representative portion thereof at the plurality of internal temperatures (T), and establishing a relationship between the determined plurality of internal temperatures (T) and the associated plurality of pulse propogation times (t T ). Thereafter the unknown internal temperature (T U ) of the object to be monitored may be found by measuring the pulse propogation time (t TU ) taken by an ultrasonic frequency pulse signal to propogate therethrough and determining the unknown internal temperature (T U ) from correlating the measured pulse propogation time (t TU ) at the unknown internal temperature (T U ) to the relationship. Where the propogation paths in the sample object and object to be monitored have significantly different lengths, the aforesaid relationship may be made independent of the dimensions of both objects.