Nano-Porous Networks Enabled Out-of-Autoclave Curing of Carbon Fiber Reinforced Plastic Aerospace Composites

Abstract

Large-scale aerospace composite parts utilizing autoclave-required carbon fiber reinforced plastic (CFRP) epoxy prepreg were manufactured with a novel Nano- Porous Network (NPN) enabled and CNT-heater based out-of-oven (OoO) for a combined out-of-autoclave (OoA) approach. While prior work has established open porosity carbon nanotube films as effective NPN materials, here we utilize electrospun polymer nanofiber veils to provide capillary pressure in the inerlaminar region during curing, thus enabling void elimination without requiring an autoclave. A CNT-based surface heater was used to cure a 0.6 m  0.6 m plate. Utilizing the fast rate of the CNT heaters, an accelerated cure cycle was developed to shorten the cure cycle by 35% compared to the manufacturer-recommended cure cycle (MRCC). X-ray microcomputed tomography (μCT) inspections showed that the cured parts (autoclave baseline and combined OoA approach) were void-free. The mechanical tests (shortbeam shear, tension, and compression) revealed that the accelerated-cure combined OoA approach composites were equivalent to the autoclave cured parts. Having attributes of reducing capital cost and increasing manufacturing efficiency intrinsic to OoA, this scaled fabrication method is a facile alternative to conventional autoclave fabrication, and future work will study a broader array of mechanical testing.