Low-cost, low frequency slotted cylinder transducer

Current ASW missions require low frequency off-board sound sources that can operate monostatically or bistatically. Since these sources may or may not be recoverable, and may require a substantial number to cover the designated operating areas, the low frequency source transducers also need to be low cost. The team of Etrema Products and Applied Research Laboratory at The Pennsylvania State University (ARL Penn State) propose using magnetostrictive Galfenol, an iron-gallium alloy, in low frequency transducer devices to produce compact, high acoustic performance transducers at relatively low production costs. Galfenol is uniquely suited for use in low frequency transducers because of its formability, relatively high tensile strength, and relatively high magnetic permeability all of which allow the use of complex shapes to drive transducers. Two Galfenol spring transducer concepts will be investigated: a slotted cylinder transducer with a Gaflenol spring instead of a piezoceramic driver, and a simple double or four headed piston with Galfenol spring drivers. Both these concepts are potentially low-cost, high performance transducer that can reach source levels in excess of 210 dB, resonant frequency less than 1 kHz, and bandwidth greater than 200 Hz.