USA as Represented by Secretary of the Navy

Robert A DeChico

James F McEachern

Timothy L Kraynak

An apparatus for producing an acoustic output in an underwater environment ncludes a radiator having a generally elongate, circular x-section with first and second ends, the outer surface of the radiator having a curved shape; an end cap attached to each end of the radiator; and a plurality of piezoceramic elements positioned and arranged to form stacks located exterior to the radiator and between the end caps. The radiator and the end caps seal off the interior of the radiator and provide an air tight cavity interior to the radiator. When a fluctuating voltage is applied across the piezoceramic stacks, the stacks are caused to longitudinally expand and contract in concert with the applied voltage thus inducing a displacement of the end caps. Since the ends of the radiator are attached to the end caps, the radiator is caused to flex inwardly and outwardly as the end caps move longitudinally. The present invention provides a greater specific power output; a useful, dry space interior to the radiator; and enhanced cooling of the piezoceramic elements.

Barrel stave flextensional projector

An acoustic array having polymer hydrophones is disclosed. The array compes a plastic roll, a plurality of polymer piezoelectric sensors affixed to the roll and electrodes that interconnect the sensors to utilization means such as those found for underwater detection systems or geophysical detection systems such as seismic detectors. The plastic roll has a pliant characteristic so as to readily assume a predetermined shape as well as, preferably, having a strong tendency to unravel and is of a relatively thin material. Similarly, the piezoelectric sensors have a pliant characteristic, are relatively thin, and are affixed to one of the surfaces of the plastic roll. Further, the electrodes have a pliant characteristic, are relatively thin, and are affixed to the same surface of the roll as the sensors. The overall effect of these thin and compliant elements is to provide an array having a high packing density, so that a relatively large array may be stored in a relatively small housing, such as that found in a sonobuoy. The high packing density array of the present invention may be arranged to form various directional type receiving of transmitting devices.

Flexible acoustic array with polymer hydrophones

An underwater transducer comprises a piezoceramic transduction layer and a etal substrate with a thin film of viscous fluid between them. The viscous film allows the transduction layer and substrate to expand and contract relative to each other when the laminate bends under increasing hydrostatic pressure as the transducer descends in a body of water. At sonic frequencies, however, the viscous film provides effectively a rigid bond between the transduction layer and the substrate so that they vibrate in unison. The invention reduces hydrostatic compressive loading on the transduction layer and thereby improves performance in deep water applications. A ring on the substrate surrounds and is engaged by the edge of the transduction layer as hydrostatic pressure increases in order to apply enough compressive stress to the transduction layer to prevent peaks in dynamic loading from exceeding the tensile limits of the transduction layer. Electrical connections are made to the face of the transduction layer opposite the face exposed to the viscous film. Viscosity effects are improved by the use of flow restricting structures. The invention can be embodied in a double bender disc transducer.

Growing community of inventors

Pennington, NJ, United States of America

Robert A DeChico