Ultrasonic stress measurements based on the generalized acoustic ratio technique

Based on the theory of wave propagation in prestressed solids, a new stress reconstruction method, the Generalized Acoustic Ratio (GAR) technique, is developed for locally plane geometries. The GAR method requires the measurement of the time of flight of the three ultrasonic wave modes (longitudinal and shear waves) perpendicular to the plane of stress and the associated shear wave polarization angles. From this ultrasonic data and calibrated material properties, the local plane stress tensor is determined. Measurements on uniaxial tension test specimens yield the acoustoelastic calibration constants.