NUMERICAL-METHOD TO RECOVER THE ELASTIC-CONSTANTS FROM ULTRASOUND GROUP VELOCITIES

This paper proposes a numerical method for the identification of elastic constants. The method is based on a least-squares fit from the ultrasonic wave group velocities, as a function of the propagation direction in the principal planes. This algorithm is deduced from considerations on the Cagniard-de Hoop contour, associated with the fact that the wave arrival times correspond to discontinuities on the waveform. Two polynomials, in terms of group velocities, are then obtained. These two polynomials are linked by the phase slowness component on the surface. The method to recover the elastic constants is applied to simulated group velocities corresponding to a real composite material.