Manufacturing of Carbon/Epoxy IsoBeam Lattice Structures

Abstract

This research demonstrated the fabrication of nominally 5 ft. (1.5 m) and 10 ft. (3 m) long carbon/epoxy IsoBeam™ structures, with a rectangular 5†(12.7 cm) wide by 10†(25.4 cm) deep cross-section. The IsoBeam structure is a composite lattice structure that is a geometric derivative of the IsoTruss® structure. IsoTruss composite structures have proven to be stiff, light-weight, and efficient in a variety of loadbearing applications. Modifying the geometry to yield a rectangular cross-section provides additional applications for these beams as structural elements in buildings, aircraft, vehicles, and other structures. Three IsoBeam structures were manufactured – two 5-foot (1.5 m) long beams and one 10-foot (3 m) long beam – with carbon/epoxy tows comprising Toray T700SC-12K-50C carbon fibers pre-impregnated with TCR Composites UF3369- 100 epoxy resin. An aluminum 3-dimensional modified pin-mandrel was designed and manufactured. The composite tows were positioned on the mandrel under tension using a combination of hand and machine filament winding to create the complex geometry of the IsoBeam structure (the complex IsoBeam geometry prohibits the filament-winding process from producing a full IsoBeam structure without hand intervention). Each member was circumferentially wrapped with overlapping 1 inch (2.5 cm) wide strips of Dunstone Hi-Shrink Tape (polyester) to consolidate the tows during the curing process. The results of this research indicate high quality manufacturing as evidenced by high volume fraction and low void ratio.