Lightweight Composite Truss Section Decking.

GAINSVILLE,Va.--(BUSINESS WIRE)--June 15, 1999--

Atlantic Research Corporation (ARC) has applied its automated 3D Through-the- Thickness(R) braiding technology to produce lightweight composite truss section decking.

The all-fiberglass deck is designed to carry the loading of an AASHTO HS 20-44 bridge or a military loading, up to the M1 tank and tank carrier.

The truss structure provides a lightweight fiber reinforced plastic (FRP) plate that can be rapidly installed for temporary decking, permanent deck replacement, or for military causeways. The edge supported composite plate can span up to 10-foot by 30-foot gaps at a weight of 20-pounds/sq. ft. The triangular elements, which make up the deck truss, can also be bonded into square or rectangular arrays to form box beams or columns.

The product form is unusual for pultrusion because the majority of the fibers are oriented over 65 degrees from the direction of pull. This results in a product with balanced strength and stiffness in all directions. Through-the-thickness fibers eliminate ply debonding at the sharp corners and provide sufficient strength to allow pultrusion of the thick, multi-directional textile. Over 2,000 fibers are used in the braided perform. The textile form allows delivery of the feedstock from a fabric roll instead of the traditional loading of individual fiber ends.

Triangular elements are fabricated using a single, thick ply of 3D-braided fiberglass textile drawn through a pultrusion die. Vinyl-ester resin is used as the rigidizing medium. The triangular pultrusions are bonded together with face sheets, using Plexus adhesive, to form bridge deck modules. Fiber balance in the face sheets is oriented along the long (pultrusion) axis of the triangle elements. Fiber balance in the pultruted triangles is oriented perpendicular to the pultrusion axis. The assembly is optimum weight for a plate over a span because the triangles carry the load with truss action and the face sheets carry the load as a beam.

The Georgia Institute of Technology, School of Civil Engineering, has tested the deck materials and structure. Long-term durability was evaluated by coupon testing after repeated freeze/thaw cycles. The average loss in strength was only 5% after 150 cycles. Flexure and buckling tests of the truss assembly have verified the 10.0 Factor of Safety. Gross deflection of the deck does not exceed 0.35 inches in an over test of 1.33 times the design load. A portion of the composite causeway deck will be installed at a Virginia Department of Transportation site on I-81 near Roanoke, Virginia. The test site is restricted to heavy vehicle loads only and measures vehicle speed, wheel loads, and deck deflection.

Development of the Truss-Section FRP deck was sponsored by the Office of Naval Research and the Federal Highway Administration. A technical report is available which describes the design concept, analysis, fabrication, and testing. A program overview is also available on CD, in a PowerPoint(R) slideshow format, and as a 15-minute video presentation.

ARC, a unit of Sequa Corporation, is a leading developer and producer of solid propellant rocket motors, gas generators, advanced composite materials and liquid propulsion systems, including the liquid propellant rocket motor line acquired from Royal Ordnance late 1998. ARC, applying its defense technology to the commercial marketplace, produces a growing line of automotive air bag inflators and supplies energetic components for the air bags from its high capacity propulsion plant in Camden, Arkansas. Please visit our web site at http://www.atlanticresearchcorp.com.

Sequa Corporation is a diversified industrial company whose other principal interests include the manufacture and repair of jet engine components, the coating of coiled steel and aluminum, and the production of specialty chemicals, can machinery, auxiliary press equipment, and automotive products. Visit Sequa's web site at http://www.sequa.com.