Electro-Magnetic Acoustic Transducer (EMAT) for both Lamb and Shear Horizontal Wave Transduction

摘要

An electro-magnetic acoustic transducer (EMAT) generates both Lamb waves and shear horizontal (SH) waves or Lamb waves only. In configurations, the EMAT includes first and second coils shifted in alignment relative to one another and a magnet array overlaid over the coils. The EMAT generates a Lamb wave when the first coil is excited with an electrical current and generates a SH wave when the second coil is excited with an electrical current. In other configurations, the EMAT includes a coil and a magnet array which are movable relative to one another between a first position and a second position shifted in alignment relative to one another. The EMAT generates a Lamb wave when the coil is excited with an electrical current while in the first position and generates a SH wave when the coil is excited with an electrical current while in the second position.