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Sensors and Devices

Dynamic capacitive sensor for the measurement of millimetre displacement of carbon composite panels: applications to aircraft materials subjected to lightning strikes

Research Background

This project aims to develop a sensor capable of measuring millimetre displacements of a material subjected to a lightning strike in the microsecond range. Such a sensor could accurately monitor material resilience by varying manufacturing methods, meshes, coatings and paints of carbon composite aerospace components when subjected to full-threat lightning strikes up to 200kA. This will give an insight into the physics of the materials, coatings and paints to withstand a strike contributing towards new, lighter and more resilient aerospace materials.

The Challenge

On average, each commercial aircraft is struck by lightning once a year. Its skin and sub-structures must withstand lightning strikes not only to keep passengers safe but also to ensure the aircraft structure is sound and continues to fly safely. Traditional conductive metallic aerospace materials dissipate lightning energy efficiently but modern non-conductive carbon composite materials are much poorer electrical conductors and, hence, require lightning protection systems, typically in the form of thin metallic mesh. Decoupled electrical and mechanical properties of such materials are fairly well understood but their combination during a lightning strike requires further work. This project aims to contribute an insight into the material’s electromechanical behaviour during a lightning strike.

Current Developments

The research takes place at the newly-established Morgan-Botti Lightning Laboratory at Cardiff University. Researchers from the School of Engineering collaborate with Airbus, Hexcel and the National Composites Centre to study and understand lightning interactions with a range of materials, structures and components.


Despite its lighter, stiffer and corrosion resistant properties, carbon composites have a distinct disadvantage in one area: conductivity. As a non-conductive material, compared to traditional conductive metals, they are far less effective at dissipating the explosive impulse current of a lightning strike. The combination of the electromechanical force with the Joule effect and other factors, such as shockwaves, all within a fraction of a second can result in extreme displacements, deflections and vibrations which may damage the structure and can contribute towards fatigue and degradation of the airframe.


The project aims to develop a new sensor to detect the change in displacement during a lightning strike and quantify the electromechanical effects on the material.

“New stiffer, lighter and corrosion resistant carbon composites are increasingly being used in aircraft skins and sub-structures, but such materials have poor electrical properties and understanding how they behave during a lightning strike is critical” Professor Manu Haddad

Impact

The Morgan-Botti Lightning Laboratory is a unique facility in academia that is fully dedicated to aerospace research. It was set up in collaboration with Airbus with support from the Welsh Government. It has built a strong network of aerospace companies through its EMC3 network. Its research activities are focused on understanding the basic phenomena and help better design of carbon composites materials and components with effective protection against lightning strikes.

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Lightning tests at the Morgan-Botti Lightning Laboratory showing test rig and sensor.

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Lightning Strike to aircraft & lightning damage to unprotected carbon composite.

 


 

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Case Study Contacts

Prof Manu Haddad
Advanced Sensors and Devices
July 2016