Enhanced Manufacturing of Complex Shape Composites with Nano-Porous Networks

Abstract

A novel composite manufacturing technique, utilizing open nanoporous materials, termed Nano-Porous Network (NPN), are used to consolidate autoclave aerospace-grade epoxy prepreg carbon fiber reinforced composite (CFRP) laminates without an autoclave. The L-shape geometry parts were cured with vacuum-bag only (VBO) and shown to be void free. Previous studies have demonstrated that various NPNs, including an electrospun polymer nanofiber veil NPN as used here, can provide capillary forces that enhance resin flow at ply interfaces to enable void elimination without requiring autoclave pressure. In this study, a complex structure (i.e., L-shape) structure is manufactured with an electrospun polymer nanofiber veil between each unidirectional (UD) IM7/8552 ply and cured in a conventional oven under vacuum following the manufacturer-recommended cure cycle (MRCC) but not using autoclave pressure. The L-shape is studied extensively in the literature and is known to have a varying pressure distribution around the radius such that voids concentrate in the corner. The cured parts (baseline autoclave and NPN VBO processed) were inspected with X-ray micro-computed tomography (μCT) and shown to be void-free in both the flat regions and the curve and showed equivalent interlaminar strength to autoclave-cured parts, similar to previously reported flat panels. Exhibiting low capital cost, low energy consumption, and high manufacturing efficiency, this fabrication method has the potential to replace conventional autoclave fabrication in the aerospace industry.