Underwater low-frequency sound producer using a rare earth alloy

摘要

An underwater low-frequency sound producer comprises vibrator units each including a magnetostrictive rod formed of a rare-earth alloy, a permanent magnet for providing a magnetic bias to the rod, prestress bolts for prestressing the rod, a coil wound on the rod for causing magnetostriction of the rod corresponding to an input AC signal applied to the coil, and first and second masses on opposite ends of the rod. The vibrator units are arranged seriatim end-to-end to define a polygon or ring centered on an axis. Connection blocks respectively connect the first and second masses of the vibrator units adjacent to each other. Vibration plates are respectively attached to the connection members. Outer and inner cylindrical boots and upper and lower plates define an annular space in which the vibrator units are disposed. The annular space is filled with oil having an acoustic impedance similar to that of the water in which the sound producer is placed for use.