System for generating or sensing transverse elastic bulk waves in solids

In combination, a body of material having a surface and adapted to support bulk shear waves;

• and a transducer for generating bulk shear waves in said material including a piezoelectric substrate characterized in having at least a two-fold axis of symmetry, said substrate having a first surface parallel to said axis and a second surface contiguous with and intersecting said first surface and parallel to said axis, said second surface of said substrate being coupled to said surface of said material, electrode means on said first surface of said transducer for generating an alternating electric field in said first surface of said substrate, the electric field vectors of said field extending perpendicular to said two-fold axis of said substrate for generating surface waves in said second surface of said substrate, said surface waves being transmitted through said substrate as deep surface waves characterized in that their intensity will attenuate to 1/e of their surface intensity value at a distance substantially greater than the thickness of said transducer along a direction perpendicular to said second surface and being transformed into bulk shear waves in said test material.

In combination, a test material defining a surface and adapted to support bulk shear waves;

• and a transducer including a substrate of piezoelectric material having a two-fold axis of symmetry and having first and second intersecting surfaces contiguous with each other and parallel to said two-fold axis, said second surface being coupled to said surface of said material, and said first surface extending outwardly of said material, electrode means on said first surface of said transducer adapted to sense bulk waves transmitted from said material and converted to deep surface waves in said substrate propagating in a direction perpendicular to said two-fold axis, said deep surface waves in said transducer being characterized in that their intensity will attenuate to 1/e of their surface intensity value at a distance substantially greater than the thickness of said transducer along a direction perpendicular to the surface on which said electrodes are mounted.