C. M. Thompson R. Y. Ting
Naval Res. Lab.---USRD, P. O. Box 568337, Orlando, FL 32856-8337
L. M. Leimer
Texas Res. Int., Austin, TX 78733
A new polyurethane formulation has been developed for use as the acoustical window for a soft sonar dome. The polyurethane is based on a 3000 molecular weight difunctional polybutyleneoxyglycol (PBOG) softblock. In addition, a moderately high trifunctional PBOG was added to increase the cross-link density for improving the polymer toughness. ``Spectra,'' an extended chain polyethylene fiber, was selected as the reinforcement fiber because it has excellent physical strength and is low in density. The lower density assists in matching the specific acoustical impedance of the composite to that of sea water. Fiber loadings up to 50% in thickness were used. Samples of this new composite were fabricated and their physical and acoustical properties were evaluated. Insertion loss of the test panel was measured in the USRD ATFI facility. The material was found to be acoustically transparent at the operating frequency range, and physically resilient to high impact loadings.