Development of Lightweight and Low Cost Advanced Structural Materials for Off-board Surface Vessels (OBVs)

Off-board vehicles deployed in littoral environments are subjected to severe operational loads, including wave slamming, high-speed collision with debris, and underwater explosions. They additionally serve as sensor platforms, and would benefit from reduced self- and radiated noise for towed array performance and mine defense. Consequently, we propose to exploit the flexibility of design offered by modern composites to achieve a novel OBV hull design integrating beneficial structural, shock, and stealth characteristics. Novel design features are threefold. First, the composite hull cross-section contains a compliant viscoelastic core material offering isolation from low-level transient events and acoustic isolation and damping, in addition to its structural function. Second, we propose a novel composite stiffener design that integrates structural function with large shock protection, by minimizing stress concentrations at structural discontinuities. Third, to address the occurrence of stress concentrations at geometric discontinuities state-of-the-art forming techniques are proposed that allow for the fabrication of highly curved junctions without appreciable loss of strength. Our proposed Phase I effort includes concept performance predictions (Applied Physical Sciences, Inc), static and dynamic validation tests (University of Massachusetts- Advanced Composite Materials and Textiles Research Laboratory), and a benefit trade-off analysis against weight and cost (Marine Applied Physics Corporation.) BENEFITS: The successful completion of the proposed effort will yield a composite hull design that significantly improves the shock and impact survivability and sensor related mission performance of the Navy's OBV or similar marine vehicles. Certain of our novel hull design features may be patentable and have application to small commercial or pleasure boats, e.g. our composite forming technique or integrated stiffener-mount design.