ACOUSTIC-WAVES GENERATED BY A LINE SOURCE IN A VISCOELASTIC ANISOTROPIC MEDIUM

The acoustic signature provided by laser-generated ultrasound in polym er matrix composites is difficult to interpret on account of the dispe rsive nature of these materials. In order to simulate such wave forms, a double numerical inverse transform is used to calculate the surface displacement generated by a line impact. This calculation method is p referred due to the frequency dependence connected with the viscoelast ic theology. The focusing effects that anisotropy gives rise to are re presented. In addition, the spreading of the signals issued from absor ption is correlated with the anisotropic changes of the slowness versu s frequency. The predicted displacements are in good agreement with th e result of experiments performed with a composite plate. (C) 1998 Ame rican Institute of Physics.