Effects of Interaction Between Stress and Temperature on Ultrasound Velocity

The work described here is part of a program to explore the possibility of employing a new concept for ultrasonic nondestructive evaluation of subsurface residual stress in metals. Theory indicates its potential applicability to characterization of stress to depths of 1–2 cm or more. The method employs a measurement of time variations in velocity in response to the inducement of time-varying thermal gradients within the stress region. The physical principle, as discussed below, is an interaction between stress, temperature and velocity