Ultrasonic Wave Interaction for NDE of Inhomogeneous Prestress in Materials

The problem of ultrasonic nondestructive evaluation (NDE) of inhomogeneous prestress field is studied theoretically for an elastic material and plane strain. The nonlinear effects of ultrasonic wave propagation and interaction are shown to be additional sources of information for NDE. A model problem of simultaneous propagation of two ultrasonic longitudinal waves in physically nonlinear elastic material undergoing two-parametric prestress state is solved. The corresponding analytical solution is derived. Results of numerical simulations lead to the conclusion that it is possible to propose an algorithm for NDE of the inhomogeneous prestress field on the basis of the recorded data of boundary oscillations evoked by simultaneous propagation of two ultrasonic waves. The analysis of the oscillating boundary profiles permits to determine qualitatively the presence of prestress in the material and to distinguish special cases of the prestress state, for example, to evaluate quantitatively the parameters of the prestress.