A HIGH IMPACT STRENGTH LOW INSERTION LOSS SONAR WINDOW

HIGH FREQUENCY, HIGH STRENGTH SONAR, WINDOWS ARE REQUIRED FOR SUBMARINE OPERATIONS AT LOCATIONS THAT MAKE THEM HIGHLY SUSCEPTIBLE TO DAMAGE FROM IMPACT OF OBJECTS IN THE WATER. DURING ARCTIC OPERATIONS THEY ARE ALSO EXPOSED TO ICE LOADS AND FAST CHANGING TEMPERATURE EXTREMES ASSOCIATED WITH SURFACING THROUGH ICE. THIS PHASE I RESEARCH STUDIES THE FEASIBILITY OF FUNCTIONALIZING POLYETHYLENE FIBERS SO THAT THE RESULTANT EPOXY OR POLYURETHANE SONAR WINDOWS POSSESS SUPERIOR STRENGTH AND REDUCED INSERTION LOSSES AT HIGH FREQUENCY. ULTRAHIGH MOLECULAR WEIGHT POLYETHYLENE FIBER WILL BE SURFACE TREATED AND THEN FORMED INTO COMPOSITES BASED ON POLYURETHANE AND EPOXY. ACOUSTIC PROPERTIES OF THESE COMPOSITES WILL BE MEASURED AND MASTER CURVES BE OBTAINED USING THE TIME-TEMPERATURE SUPERPOSITION TECHNIQUE. TENSILE STRENGTH WILL BE USED TO EVALUATE THE EFFECTS OF SURFACE TREATMENT ON COMPOSITE STRENGTH. IF SUCCESSFUL, THIS RESEARCH WILL IDENTIFY NEW ACOUSTIC MATERIALS FOR USE IN HIGH FREQUENCY SONAR DOME APPLICATIONS. PHASE II WILL INVOLVE FURTHER TESTING OF COMPOSITES, SELECTING THE BETTER COMBINATIONS OF MATERIALS BASED ON THESE TESTS, AND WRITING PROCUREMENT SPECIFICATIONS FOR INCLUSION IN THE SYSTEM PROCUREMENT SOLICITATION FOR PHASE III.