Tuesday, 12 October 2004 - 1:00 PM

This presentation is part of : Damage and Composites I

Composite Materials in Modern Ship Structures (Keynote Lecture)

Yapa D. S. Rajapakse, Office of Naval Research, Office of Naval Research, Arlington, VA 22217

Composite materials are being used increasingly in many challenging applications, including high performance Naval structures. The unique marine environment (with the presence of sea water and moisture, varying temperatures, and time-dependent three-dimensional loading due to wave slamming and other factors) provides many challenges to the Navy design community. In addition to the requirements imposed on commercial ship structures, Naval structures are required to withstand highly dynamic loading during combat situations, due to weapons impact, or to air or underwater explosions.

The Solid Mechanics Research Program at the Office of Naval Research provides the scientific basis for the effective design of affordable Naval structures , including composite and composite sandwich structures. This program deals with the response of glass fiber and carbon fiber reinforced composites and composite sandwich structures, to static, cyclic, and dynamic multi-axial loading conditions. The sandwich structures of interest utilize PVC foam cores and balsa wood cores, with composite face sheets. An overview of this Navy - unique research program will be provided, with a discussion of its objectives, research issues, recent accomplishments, and future directions. The major focus is on the establishment of physically based models for deformation and failure.

Specific topics discussed will include: failure modes and failure criteria; dynamic constitutive behavior and strain rate effects; dynamic failure modes; intersonic crack growth; the effect of moisture and sea water absorption; fatigue; failure modes in sandwich structures; and impact damage in sandwich structures. The use of nanoparticles for enhancing the performance of marine composites will also be discussed.

Examples of ship structures utilizing composites in Europe and in the U.S. will be described. These will include the VISBY corvette, SKJOLD surface effects ship, FLYVIFISKEN multi-mission ships, and OSPREY mine-hunters. Current design plans for the new generation of U.S. Navy ships, DD(X), and other ship systems, include the use of composites. Applications of composites in underwater structures will also be discussed.

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