NEW METHOD FOR DETERMINATION OF APPLIED AND RESIDUAL-STRESSES IN ANISOTROPIC MATERIALS FROM ULTRASONIC VELOCITY-MEASUREMENT

A novel technique for absolute stress determination in orthotropic mat erials from angular dependencies of ultrasonic velocities is described . The technique is applicable for determination of both applied and re sidual stresses and does not require calibration measurements on a ref erence sample. The important advantage of Mis method is that Me stress is determined simultaneously with stress dependent elastic constants and is thus decoupled from Me material texture. It is demonstrated tha t when the principal plane stress directions coincide with acoustical axes, the angular velocity data in the plane perpendicular to the stre ss plane may be used to determine both stress components. When the str ess is off the acoustical axes, Me shear and the difference of Me norm al stress components may be determined from the angular dependence of group velocities in the plane of stresses. Synthetic sets experimental data corresponding to materials with different anisotropy and stress levels are used to check the applicability of the technique. The metho d is also verified experimentally A high precision ultrasonic wave tra nsmission technique is developed to measure angular dependence of ultr asonic velocities. Examples of stress determination from experimental velocity data are given.