Z-shaped magnetostrictive patch for efficient transduction of a torsional wave mode in a cylindrical waveguide

An earlier investigation [C. I. Park , Appl. Phys. Lett. 87, 224105 (2005)] using topology optimization showed that if V-shaped yokes are attached to magnetostrictive strips obliquely bonded on the surface of a cylindrical waveguide, the transduction efficiency of ultrasonic torsional waves can be substantially increased. However, some unwanted wave modes are also generated unless some damping treatment is applied. This investigation shows that if the strips are reconfigured as Z-shaped patches, the transduction efficiency gained by the optimization technique can be maintained without the generation of unwanted modes. By experiments using the Z-shaped patches, the transduction characteristics including the frequency characteristics of an ultrasonic torsional wave are also investigated. (c) 2006 American Institute of Physics.