Western Mail Profiles: Dr Rhys Pullin, Cardiff University

‘We can continue to grow and develop aircraft sector’
Dr Rhys Pullin
is a lecturer in the School of Engineering at Cardiff University. In this article, the first of a series in the Western Mail by the cream of Welsh research talent, he discusses his work into weight reduction of aircraft through new materials, and detecting damage in these materials as it occurs

The next generation of aircraft will use new composite materials such as carbon fibre reinforced plastics, currently found in Formula 1 racing cars and wind turbines.

These materials are made from cloth weaved from carbon fibres captured within a plastic resin and are extremely light- weight and strong when compared with more traditional metals.

The use of these materials will significantly reduce the weight of the next generation of aircraft and hence will reduce harmful emissions ensuring that the increasing air traffic use will have a minimum impact, keeping our skies clean.

These materials do not come without their drawbacks. Composites can suffer from impact damage such as bird strike or accidental collisions which in some cases reduces their overall strength and may compromise safety.

This damage cannot always be seen during routine maintenance so systems that can detect the damage as it occurs are necessary to fully realise the potential of composite aircraft.

Acoustic emission is a technique that relies on the detection of stress waves released within a material due to damage occurring.

The technique is often compared with earthquakes but on a microscopic scale and, like earthquakes, the epicentre of damage can be determined by examining the arrival of a wave at a number of monitoring points.

By applying acoustic emission to composite structures it is possible to monitor and analyse damage continually.

My research in acoustic emission began with its application to bridge structures, and a number of bridges not only in Wales and the UK, but also world-wide, have been monitored for damage using the technique.

In one example of the application of the technique, a bridge structure was able to remain open during vital maintenance, which prevented traffic and travel disruptions. This work has progressed to the assessing of new designs of landing gears during certification tests and has resulted in the current project to monitor other aircraft components.

The current application to new materials is linked to the ability to capture energy from the ambient energy available in flight (such as temperature difference and vibrations) in order to provide a lightweight autonomous health monitoring system which is able to transmit information wirelessly.

It is anticipated that the wires which normally connect sensors and communicate information can be removed, saving several miles of cables on each plane again minimising aircraft weight. Within a few years such systems will be used in aircraft to support the environment.

Over 180 companies in Wales employing in excess of 20,000 people rely on the aircraft industry and through the establishment and completion of research projects within the university in conjunction with the world leaders in aircraft design, we can continue to grow and develop the sector.

To contact Rhys email PullinR@cardiff.ac.uk

This article first  appeared in the Western Mail‘s Health Wales supplement on the 18th July 2011, as part of the Welsh Crucible series of research profiles.