Medium-range magnetostrictive ultrasonic guided wave scanner systems and methods

A method for non-destructive inspection of a structure, comprising:

• applying a biasing magnetization to a ferromagnetic strip that is coupled to the structure such that the ferromagnetic strip extends at least partially around a circumference of the structure;
• moving a scanner probe in a first direction relative to said structure along said ferromagnetic strip that extends at least partially around the circumference of the structure, the scanner probe supporting at least one sensor coil and an encoder;
• applying a time-varying current in the at least one sensor coil to induce a time-varying magnetization in said ferromagnetic strip to generate shear horizontal-type guided wave energy into said structure as the scanner probe is moved in the first direction relative to the structure, the shear horizontal-type guided wave energy propagating through the structure in a second direction that is different from the first direction;
• detecting reflected shear horizontal-type guided wave energy as the probe is moved relative to said structure;
• and
• processing the reflected shear horizontal-type guided wave energy and positional data received from the encoder to generate at least one two-dimensional image of a region of said structure.

A system for non-destructive inspection of a structure, comprising:

• a magnetostrictive scanner probe including a probe body for supporting at least one flexible sensor coil and a position encoder;
• a ferromagnetic strip configured to be coupled to the structure;
• at least one magnet for applying a biasing magnetization to the ferromagnetic strip;
• and
• a processor configured to
• cause a time-varying current to be generated in the at least one flexible sensor coil to induce a time-varying magnetization in said ferromagnetic strip perpendicular to said biasing magnetization to generate shear horizontal-type guided wave energy into said structure, and
• process reflected shear horizontal-type guided wave energy received by the at least one flexible sensor coil as the probe is moved relative to said structure to generate at least one two-dimensional image of a region of said structure;
• wherein the at least one flexible sensor coil includes at least two flexible sensor coils, the at least two flexible sensor coils supported by the probe body such that they are arranged parallel to a direction in which the shear horizontal-type guided wave energy propagates, and
• wherein the processor is configured to cause pre-determined time delays to pulses applied to the at least two flexible sensor coils for suppressing forward- or reverse-propagating waves from the probe.