Mesure simultanée de la vitesse de phase, de l'atténuation des ondes ultrasonores, de l'épaisseur et de la masse volumique de matériaux composites

Abstract
Under impact, the geometrical and mechanical properties of materials are modified. In composite materials, the damage is due to delamination between plies and macro-cracking appearance inside the matrix. These induce large modifications in velocity and attenuation of ultrasonic wave. Because thickness and density of the impacted material can also be influenced, we propose a simple ultrasonic method to measure these four properties in the same time. Plate thickness and wave velocity are deduced from the time of fly of several echoes, attenuation and density are obtained from a spectral analysis of these echoes. We test the method on three different materials : glass, PVC, glass/epoxy. The results obtained are quite good. In a further work, we will extend this method to focal probe, to increase spatial resolution.