SBIR-STTR Award

The widespread use of advanced composites has been severely impeded by the lack of an economical fabrication technology. The advantages of the Pultrusion Process in this regard have long been recognized by the composite community, and part shaping of pultuded sections has been identified as a promising means of producing a range of structural components in recent cost modeling initiatives (NASA/ACT). However, the major drawback of the process is the restriction to linear cross section (prismatic) components. Practicable reshaping techniques and methods of imparting complex curvatures are now being developed. This work combines controlled thermal distortion with recently developed Selective Interval Pulshaping Technology to provide a processing strategy to produce circumferencial and longitudinal stiffening elements of aircraft fuselage and other aerospace structures, with process economics exceeding any existing by at least a factor of two. Proprietary techniques will be used to produce elastomeric matrix sections to provide structures with enhanced vibration damping. Full scale pultrusion trials will be carried out in conjunction with analytical and numerical modeling activities to establish the feasibility of developing fabrication technologies applicable to both BMDO needs and commercial opportunity.

Advanced composite structures employing elastomeric matrix resins and typically having greater than 50% fiber reinforcement by volume have been fabricated. Analysis tools for prediction of curvatures in purposely unbalanced lay-ups have been developed and products targeted which require extreme stiffness values and/or passive vibration control via discrete axis damping. Exhibiting a single very high performance axis and several motion accommcodating axes, novel power transmission couplings have been developed for filament winding with low cost and high misalignment capability. By use of a controlled thermal distortion technique similar fiber reinforced elastomers have been processed via pultrusion such that an alpine ski can be produced continuously with prescribed camber upon cool down from the cure temperature. High pressure injection of viscous, short pot life resins was accomplished. Winding of hybrid helicopter blade retention straps is proposed whereby extreme torsional motion is accommodated while finessing of the stiffness matrix allows tensile strength to be doubled over previous technology Missile and similar fuselage type structures can benefit from the commercialization of the above target applications via fabrication of highly damped, low cost, discretely stiffened shells.