University of Wisconsin-Madison engineers have developed a flexible composite material designed to protect aircraft from lightning strikes while overcoming limitations of conventional metallic protection systems. The hybrid material combines carbon fiber fabric with woven stainless steel yarn, creating a conductive outer layer that can conform closely to complex aircraft surfaces.
Carbon fiber-reinforced polymers are increasingly used in aircraft because they offer high strength at relatively low weight. However, their poor electrical conductivity creates a problem during lightning strikes. Electrical energy can become concentrated near the strike location, generating intense heat and damaging the composite structure.
Led by associate professor Pavana Prabhakar, the researchers incorporated stainless steel yarn directly into carbon fiber fabric. Two metal-infused woven layers are positioned perpendicular to each other, creating pathways that spread electrical charge in multiple directions. Applied near an aircraft’s exterior, the material works somewhat like a fabric-based Faraday cage, distributing charge across a larger surface and reducing localized heating.
The approach could improve on expanded metallic foil, which is commonly used for lightning protection. Foil systems can contribute to delamination during strikes and can be difficult to fit around complicated geometries. The new fabric is drapable, making it potentially useful for unconventional aircraft, drones, and emerging air taxis.
Simulated lightning tests produced encouraging results. One hybrid sample lost only 0.03% of its weight after exposure, compared with material losses as high as 3% in composites without metal reinforcement. Bending tests also indicated that the protected material maintained its structural integrity after lightning exposure.
The protective layer could be incorporated during aircraft manufacturing or bonded onto existing structures for retrofits and repairs. The researchers now plan to investigate copper yarn, long-term durability, galvanic corrosion, and metal-coated carbon fibers as they work toward improving the technology for practical aerospace applications.
