Acoustically Transparent Underwater Curing Adhesive

Navy submarines are incorporating an increasing number of sonar conformal surfaces. The materials that comprise these surfaces act to contain the sonar components while maintaining or enhancing the acoustic performance of the resulting sonar signals. These materials break down over time through physical damage, material degradation, and biofouling, causing degradation of the acoustic performance. The Navy is looking for an acoustically transparent adhesive which can be used to fill and fair any damaged sections of conformal material without the requirement for drydock. Texas Research Institute Austin, Inc. (TRI Austin) proposes the modification of our preexisting commercial elastomeric polyurethane into an Acoustic Underwater Repair Adhesive (AURA). To demonstrate viability of our proposed approach, TRI Austin has shown that this polyurethane possesses an acoustic impedance very similar to that of water at tested frequencies. Preliminary AURA testing has demonstrated the capabilities of this adhesive to dispense, fair, and cure, while submerged in salinated water. In this effort, TRI Austin will partner with Nelson Acoustics to ensure that AURA meets all acoustic requirements for repair of conformal sonar surfaces. Phase I will demonstrate the ability of AURA to meet the acoustic, curing, adhesion, and thermomechanical properties desired for this application. Phase II will continue this work, further the applied acoustic and repair testing, and scale AURA to relevant quantities. Phase III will see the transition of AURA to the Navy, DoD, and commercial sector customers.Ý