Automated stress analysis by ultrasonic testing

Ultrasonic testing techniques yield information on residual stress conditions at the surface and in the body of a specimen or component. The testing principle uses the effects of elongation states on the propagation rate of ultrasonic waves. By combining two wave modes evaluation relations are obtained, with the travel times of ultrasonic waves being the only measured quantities in them. Computed analysis of stress in component parts relies on automated measurement of the ultrasonic wave travel time, as affected by elongation, and stress conditions are calculated by means of the material-specific elasticity constants. A universal measuring device has been built and tested that automatically measures the travel times and computes the absolute stress values, or stress differences, with recourse to evaluation relations stored in the memory which are defined for every specific testing task. (orig.)