Measurement of Residual Stress Using the Temperature Dependence of Ultrasonic Velocity.
Interim rept. Jun-Dec 82,
HOUSTON UNIV TEX DEPT OF MECHANICAL ENGINEERING
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The temperature dependences of ultrasonic velocities are due to the an-harmonic nature of the crystal lattice, and therefore can be used for stress measurements. Experiments performed on 6061-T6 aluminum show that, in the vicinity of room temperature, the ultrasonic longitudinal velocity decreases linearly with temperature, and the slope of the linear relationship varies considerably when the specimen is subjected to stress. For compressive stress applied perpendicular to wave propagation, the temperature dependence of the velocity is found to decrease linearly by as much as 20 at a stress of 80 MPa. The results also indicate that the relative changes in the temperature dependence of velocity as a function of stress are equal to those previously obtained on other aluminum alloys. This shows the insensitivity of the temperature dependence method to texture and alloy composition. The method thus offers a promising possibility for the nondestructive measurement of residual stress. Author