Wireless frequency-tuned generation and measurement of shear horizontal waves using magnetostrictive gratings in plates

The wave transduction method can be used in various nondestructive evaluation applications if shear horizontal (SH) waves are generated and measured successfully in plate structures. We consider using the principle of magnetostriction as an efficient means for generating and measuring SH waves, because the energy conversion between magnetic energy and acoustic energy in magnetostrictive material can take place wirelessly. A grating-type magnetostrictive transducer was considered because SH waves at desired frequencies can be tuned by changing grating size and distance. Experiments showed that grating width should be selected appropriately to avoid generating unwanted wave modes such as the Lamb wave modes. The experiments confirmed that the grating distance controls the center (or tuning) frequency of the grating transducer.