Thin-ply prepregs offer significant improvements in weight reduction, stiffness and overall mechanical properties over traditional composite laminates. Thin plies (<0.05 mm/layer) suppress or delay crack initiation in loaded composite structures thereby allowing for manufacturing of lighter, stiffer and more durable composite products. Recent thin-ply prepreg materials, consisting of toughened epoxy, cyanate ester and bismaleimide (BMI) resins, have been developed specifically for out-of-autoclave (OOA) manufacturing that answers the growing need of aerospace, space and other industries for processing large composite structures at reduced costs.
Touchstone Research Laboratory, Ltd, proposes to manufacture a self-heated composite tool for thin-ply prepreg OOA processing. A high in-plane heat spreader material will be utilized to reduce temperature gradients on the tool surface thus improving cure heat rates and temperature uniformity, which are critical for long span and large surface area composite structures. Touchstone and Clemson University propose to manufacture thin ply composites from unidirectional prepreg tapes for breadboard testing in Phase I and prototype testing in Phase II. Areal weights of the thin ply composites are targeted to be less than 60 g/m². OOA processing of thin ply prepregs potentially eliminate expensive autoclaves and ovens impracticable for manufacturing large structures.
NASA has interest in thin-ply technology for large structures such as deployable booms for solar sails, solar arrays, and communication antennas. Prepreg-based OOA methods are critical for processing next generation heavy launch vehicles. Given the component size and low production volumes, OOA processes are key to keeping costs low. Recent success in developing OOA carbon fiber/BMI prepreg shows that it is possible to achieve satisfactory results for the application.
The general approach and specific technologies developed in this STTR can also be applied to other commercial applications such as Airbus A340 & A380 fixed wing leading edges, keel beam ribs, and Boeing 787 pressure bulkheads. Other military Aerospace and Wind applications that demand high stiffness are also potential candidates.