Composite Joints for Mechanical and Electrical Performance

TWI is working in collaboration with Cranfield University to explore new and innovative aircraft lightning strike technology. TWI contributes its strong experience in the joining of dissimilar materials and in coating technologies for composites.

Background

Lightning strikes are a common event to aircraft, with high voltage strikes capable of causing considerable damage. This damage occurs as a high energy electrical current passes through the aircraft structure to reach a point where it can discharge into the atmosphere. Current aircraft design incorporates a range of mechanically fastened structural joint assemblies, which are often located in the electrical current path and reduce electrical conductivity performance. On post lightning strike inspection, these joint assemblies are subject to damage and require repair.

The C-JOINTS project is tasked with looking into exploring the options and identify improvements to the performance of electrical conductivity within the aircraft structural joints. A direct result of improved electrical conductivity will be a reduction in aircraft damage during a lightning strike event.

Objective

To explore the structural and electrically conductive performance of composite joint assemblies through:

Incorporating through thickness electrically conductive reinforcements. This will support electrical current flow through individual composite components, whilst providing structural performance
The application of electrically conductive coatings to composite component mating faces. This will support the electrical current flow through non-metallic joint assemblies
The application of laser rivet technology to composite / metallic joint assemblies, to replace conventional metallic airframe fasteners. Removing conventional fasteners from the path of the electrical current will improve the conductive performance and introduce aircraft weight-saving benefits.

Programme of Work

TWI are currently performing tests to evaluate the comparison between existing technology and the proposed innovative alternatives. Specimens are subject to mechanical tests to establish strength parameters. Specimens are also subjected to electrical testing including high current and lightning strike.

TWI will compare test results and evaluate between the existing technology and the innovative alternatives. It is expected to make the recommendation of innovative solutions to the customer and suggest areas where they may be applied.

Future Developments

TWI are looking towards developing the technology to support other comparable joint assemblies within the aerospace industry.

The C-JOINTS project has received funding from This project has received funding from the Clean Sky 2 Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme under grant agreement No 755609.

Through thickness electrically conductive reinforcements

Chris Ruffell Composites Engineer - Adhesives, Composites and Sealants

Chris Ruffell is a composites engineer and project leader at TWI Ltd. He co-ordinates and supports research activities for the Adhesives, Composites and Sealants department.

Chris has 15 years of experience at the cutting edge of the composites industry, carrying out the development, qualification and manufacture of thermoplastic and thermosetting polymer composites. His process experience derives from career progression through industry roles including laminator, technician grades and engineer roles.

Chris’s strengths include new process implementation, process defect resolution and continuous innovative process improvement.

Chris’s industry experience includes work within aircraft, defence, space and motorsport. Chris has supported composite development for corporations including Boeing and Airbus and he has received high status recognition for innovation.

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