Patent ID: 7821258

Claim:
A method of nondestructive testing of a structure using magnetostrictive techniques to determine defects in the structure, said method comprising the following steps: first creating a permanent magnetic field at a location in said structure, said permanent magnetic field having a constant bias direction; applying a pulse of alternating current to an AC coil adjacent to said location; second creating an alternating magnetic field pulse at said location from said pulse of said alternating current, said alternating magnetic field pulse being perpendicular to said constant bias direction and parallel to a surface of said structure; generating a torsional guided wave from said alternating magnetic field pulse, direction of propagation of said torsional guided wave being in the same direction as said constant bias direction; reflecting said torsional guided wave off said defects in said structure; detecting said reflected torsional guided wave; and processing said detected reflected torsional guided wave to determine size and/or location of said defects.