Making light of damage

Composite fibres could be used as optical sensing devices, using light to illuminate damaged areas of an aircraft structure, in research soon to begin in the UK.

Researchers at Bristol University, led by Dr. Ian Bond, will investigate the use of embedded triboluminescent crystals, which emit light when cracked open, within the fibres of composite structures.

‘We could incorporate these within the fibre, so that if you do get damage to the structure you actually get some light emitted from within the fibres,’ said Bond.

Using these crystals, the hollow composite fibres could act in a similar way to optical fibres, alerting maintenance teams to areas of damage within the structure, he said. Internal damage to composite structures is notoriously difficult to detect.

‘We could potentially make our fibres operate as optical fibres and transmit the light down to wherever you want to pick it up, to detect the area of damage.’

The work will follow on from previous studies by researchers at the Defence Evaluation and Research Agency (now Qinetiq) into the use of triboluminescent materials as embedded damage sensors. The materials detected damage throughout the structure, when used in resins and glass fibre-reinforced plastic composites.

Bond plans to investigate the materials using funding from the EPSRC. ‘So far we haven’t pursued this in any great depth, but in theory it can be done, and it is a way of putting another function into the fibre, making it act as a structural reinforcement and some sort of damage sensor, in a passive way. The whole concept is to try to add more functionality to structural devices.’

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