A method is shown for magnetostrictive testing of structures using a magnetostrictive strip and magnetostrictive techniques. A torsional guided wave is generated in the magnetostrictive strip which is dry coupled or bonded to the structure. A magnetic field creates an induced bias along the longitudinal axis of the magnetostrictive strip, which magnetic field is sufficiently strong so that when an AC pulse applies an AC bias perpendicular to the induced bias, the AC bias does not override or saturate the induced bias. This allows for an increased signal to noise ratio in a reflected signal indicating a defect in the structure. The induce bias and the AC bias are created by respective windings around the magnetostrictive strip, which windings are perpendicular to each other.
Sergey A. Vinogradov