The University of Central Lancashire (UCLan) has been conducting a programme of application development for graphene enhanced carbon fibre composites under the guidance of engineering innovation manager, Billy Beggs.
UCLan’s Prospero UAV flew at Farnborough 2016 and it is aiming to be able to do so again at this year’s show. This productive technology partnership with advanced material company, Haydale Composite Solutions shows no sign of abating and is starting to draw in interest from aerospace and defence primes.
“The 3m Prospero wing was conventionally designed in a four-ply skin over a foam core configuration,” Beggs explains. “The same geometry required only a single ply of the graphene enhanced prepreg, with a 40% increase in impact damage resistance - and a 20% increase in strength.”
Although the overall structural engineering of smaller UAVs - especially in the sub-20kg group isn’t particularly demanding, weight and hence available payload is still the biggest engineering issue.
The Prospero project has centred on graphene enhanced carbon fibre composites. Graphene is a single atomic layer of pure crystalline carbon, with incredible material properties in the areas of mechanical strength and energy transfer.
Haydale Composite Solutions has a proprietary blending system enabling it to be placed where it’s required. Around 2% resin volume is composed of the graphene.
“If you just throw graphene into a resin system it will create clumping or material hotspots,” Beggs continues. “Proper suspension of the nanoparticulate allows the graphene enough particulate separation to behave as a 2D material.”
Partner Haydale Composite Solutions has provided the material, but most manufacturing has been performed within UCLan. Haydale has supplied UCLan with graphene enhanced material in the forms of carbon fibre prepreg, a thermoplastic 3D printing filament and printable ink.
Weight and strength properties
The two overriding beneficial factors are weight and strength. UCLan is getting better results on both of these using existing tooling and manufacturing technology, so this could be introduced easily into any carbon manufacturing setup. Health and safety issues on the shopfloor are eliminated, as the potentially hazardous nanoparticulate is contained within the resin rather than in a dry powder form.
The team from UCLan’s Engineering Innovation Centre went into space last month, achieving a CubeSat launch to near space to compare the performance of comparative graphene enhanced and conventional carbon fibre structures. For the design of the trial CubeSat enclosure, the graphene enhanced version came out 15% lighter. There were also enhanced thermal properties, which is highly relevant at the -60°C temperature this miniature satellite experienced. Both thermal and electrical interlaminar conductivity are increased dramatically with the addition of the small amounts of graphene.
In other work, early R&D has been conducted using a matrix of graphene ink sensors printed on a thin film. This could be introduced into rain erosion tape for damage sensing on leading edge and intake surfaces. UCLan has reached the point of component demonstration, including the software to run the damage location. It is also 3D printing with this material in filament form, and has flown a mock-up antenna and structure.
The first Farnborough Airshow flight demonstration in 2016 provided the momentum for the UK’s Aerospace Technology Institute to ask Manchester University’s National Graphene Institute (NGI) and UCLan to produce their strategy for the aerospace development and application of graphene. UCLan has since been working closely with NGI and its industrial partners, which include Airbus, Rolls-Royce and Lockheed Martin.
The UAV which UCLan want to display at Farnborough International 2018 will use the graphene enhancement over all the airframe this time, not just the wing, and will include the printed conformal antenna.
As Beggs summarises: “This is still the only graphene flyer. Lots of people have all the bits, but don’t yet know how to make the pie.”