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Cost-Effective Technologies for Fabrication of PiezoCrystal Vector Velocity Sensors


OBJECTIVE: Devise and demonstrate cost-effective methods for the fabrication of vector velocity sensors from relaxor piezoelectric single crystals. DESCRIPTION: Arrays of vector velocity sensors provide major system gains over legacy arrays of omnidirectional hydrophones in bottom moored and submarine/unmanned undersea vehicle (UUV) towed applications. For example, the left-right ambiguity of legacy devices is eliminated and an array sensitivity null can be steered at a noisy source of interference making much quieter targets detectable. The exceptionally sensitive, compact accelerometers made possible by the new relaxor piezocrystals are the key enabler for this performance enhancement. Since these sensors are only millimeters in size and are required in large numbers, a major technical hurdle for this technology is to devise cost-effective ways to manufacture the vector sensor. A cost model, relating the component and touch labor costs, is needed for the various design options. Once the dominant cost drivers have been identified, approaches to reducing costs, either through reducing component or labor costs, are essential if the Navy is to benefit from the new technology. A variety of accelerometer designs are under development for these vector velocity sensors, for example, cantilevered-beams, shear-mode, and pressure-gradient devices. While acoustic performance is the primary driver in the choice of device configuration, cost will ultimately determine the acquisition choice. PHASE I: Devise cost-effective innovative technologies to fabricate high-performance vector velocity sensors. Design, build, and test a vector velocity sensor incorporating at least one of these innovations. Estimate production costs when these technologies are introduced into volume production. PHASE II: Devise a full set of technologies to make vector velocity sensors which optimize both performance and cost-effectiveness. Demonstrate performance using appropriate in-water testing. Devise a cost model for volume production. PHASE III: Using the optimum production route devised, these technologies will be used to produce vector velocity sensors in Navy acquisition programs. PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Vector velocity sensors have a variety of civilian sector applications that would profit greatly from the enhanced sensitivity and reduced size and noise levels afforded by the piezocrystal technology. Most closely paralleling the Navy's interest in undersea towed arrays are similar towed arrays used by the oil exploration industry. In a different context these sensors are employed in vibration sensing/suppression in HVAC systems and in heavy machinery (e.g., for example for machine tool control).
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