Traducteurs ultrasonores large-bande à profil vibratoire non uniforme. Théorie et expériences

Abstract

This paper follows a strictly theoretical one presented in the previous CFA [I]. We had shown the advantage of using nonuniformly excited transducers in wideband pulse-echo method for nondestructive tetsing. We can now produce the source (and sensitivity) profile we want by a masking method not detaiIed herein. We limit the study to planar disc transducers. The transient field radiated by a planar transducer vibrating with a conventional uniform profile is often described as a superposition of a plane wave and edge (diffracted) waves. We consider three different profiles: uniform profile, profile favoring the plane wave component and another favoring the edge wave. We first compare theoretical with measured echo-responses from simple-shaped targets proving the validity of the masking technique. Then, practical transducers are studied in terms of their axial or radial resolution and sensitivity.