Application of the acoustic anisotropy approach for technical diagnostics of structures with large plastic deformations

The article is concerned with the possibilities of the application of the standard method for measuring acoustic anisotropy to the estimation of the degree of plastic deformation. Solutions to the problem of propagation of a sound wave in an isotropic elastic-plastic material are obtained and analyzed. The dependences of the velocity of longitudinal and transverse waves of different polarization on plastic strain are derived. It is shown theoretically and experimentally that the absolute value of the velocity of sound wave propagation has a monotonic dependence on the strain magnitude, while the value of the acoustic anisotropy demonstrates a nonlinear and non-monotonic dependence on the strain magnitude. The data obtained allow one to develop a methodology for assessing the magnitude of plastic strain based on the absolute values of pulse time delay measured by means of the standard industrial equipment developed for acoustic anisotropy.