N093-191 TITLE: Multi-Material Structures

TECHNOLOGY AREAS: Ground/Sea Vehicles, Materials/Processes

ACQUISITION PROGRAM: VIRGINIA Class Submarines, NAVSEA PMS450, ACAT I

OBJECTIVE: The basic need is to develop structurally robust methods for transitioning from one form of fiber reinforcement in areas that connect to steel components to areas where the higher stiffness and strength offered by alternate reinforcements can produce a significant weight savings.

DESCRIPTION: Minimizing corrosion is a constant challenge to the ship design community. Fiber-reinforced plastics are generally corrosion resistant; in fact aramid and glass fiber reinforced composites may be fastened or joined with almost any fastener material to metals without fear of galvanic corrosion. Plastics reinforced with carbon fibers can induce galvanic corrosion in the attached metal structures, or metal fasteners. This topic seeks to identify and demonstrate concepts for transitioning between two or more materials in marine composite structures while minimizing galvanic corrosion.

PHASE I: Conduct R&D and analysis to develop concepts for transitioning fiber reinforced materials and demonstrate the feasibility of the concept with respect to its use in the marine composite environment. Prepare a report on the results with recommended concept(s). In addition to structural and galvanic performance, address its manufacturability, and durability aspects in the Phase I option.

PHASE II: Develop and demonstrate the concept at the component level (i.e. a sandwich or stiffened panel and representative joints) showing the performance capabilities of the system. Also demonstrate examples of manufacturability and durability of the system through testing.

PHASE III: Insert the product into a candidate marine application and test as part of other technology demonstrator activities.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: The material technology developed under this topic could be applied to any sea, land or air vehicle where tailoring physical and/or mechanical properties provides performance improvements required by the system.

REFERENCES:
1. Tsai and Hahn, "Introduction to Composites", Technomic, 1980.

2. Telegadas, "Best Practices for Composite Submarine Non-Pressure Hull Structure", NSWCCD-65-TR-2008/28, Dec 2008.

KEYWORDS: Composites, GRP, glass, carbon, graphite, hybrid, joints, galvanic corrosion

** TOPIC AUTHOR (TPOC) **

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