THE USE OF ELASTOMERIC INTERLEAF LAYERS TO IMPROVE THE STRENGTHS OF COMPOSITE UNDERWATER PRESSURE HULLS

THICK COMPOSITE PRESSURE HULLS MADE TO DATE HAVE EXHIBITED POOR COMPRESSIVE STRENGTH WHEN COMPARED TO THIN LAMINATED ALLOWABLES. A TRANSVERSE TENSILE FAILURE MECHANISM IS THEORIZED WHICH IS CONSISTENT WITH PREVIOUS TEST RESULTS. THE USE OF ELASTOMERIC INTERLEAVES TO DIVIDE THE THICK LAMINATE INTO A SERIES OF THIN SUBLAMINATES IS PROPOSED AS A MEANS TO INCREASE COMPRESSIVE STRENGTH. THIN GR-EPOXY LAMINATES WITH INTERLEAVES HAVE EXHIBITED A FOUR-SIXFOLD INCREASE IN FRACTURE TOUGHNESS. THE INTERLEAVES WILL ALSO IMPROVE THE HULL ACOUSTIC DAMPING AND WILL AID IN LAYERED DEBULKING AND CURING WHICH WILL ELIMINATE FIBER WRINKLING AND UNEVEN CURE PROBLEMS WITH THICK LAMINATES. THE PHASE I PROGRAM WILL INVOLVE DESIGN, FABRICATION, AND COMPRESSION TESTING OF 10 IN. DIAM 0.5 IN. THICK RING SPECIMENS WITH AND WITHOUT INTERLEAVES. PHASE II WOULD INVOLVE DESIGN FABRICATION AND HYDROSTATIC TESTING OF A FULL SIZE TORPEDO HULL SECTION WITH INTERLEAVES.