Variations of ultrasonic wave attenuation in thick-walled cylinders subjected to a thermal gradient

Accurate ultrasonic testing of engineering components like pressure vessels, which are subjected to extreme condition such as high stresses, high temperatures, and thermal gradients is important. Wave velocity and attenuation are two major parameters in ultrasonic testing. In this paper, a mathematical model is developed for calculation of the absolute attenuation of longitudinal waves in thick- walled cylinders that are subjected to thermal gradients. The cylinder is assumed to be homogeneous and isotropic. The independent variables are cylinder inner and outer radii, incidence angle and temperature of the inner surface of the cylinder in the range of 300- 800 K. Based on the results obtained from the theoretical model, the wave attenuation is found to be highly sensitive to inner-surface temperature of the cylinder; however, the overall variation of the attenuation with respect to changes of the incidence angle and inner and outer radii of the cylinder is only 2 dB/m, which is ignorable in most practical applications. Furthermore, in the presence of a thermal gradient, there is an inverse relationship between the cylinder thickness and attenuation coefficient. The mathematical model is verified by using the experimental data available in the literature.