Project to look at best way to find defects in aircraft and racing cars
(NC&T/UB) The project will compare the effectiveness of various forms of thermography, a method which examines the way heat flows across the part being inspected for safety. Cracks that could lead to the failure of the part will trap heat and this shows up on infra red camera scans.
Establishing a quick and accurate way of inspecting for cracks and other damage is becoming more important as more aircraft, racing cars and other engineering structures are made from carbon composite material rather than metal, to reduce weight. Unlike metals, composite fibres can receive an impact, such as, in the case of aircraft, from a stone on take-off or a hailstone in flight, and show no obvious sign. Yet they may be extensively weakened beneath the surface.
This is because the composite consists of layers that are glued together and any impact can make the carbon layers come apart from the glue – this is beneath the surface and invisible to the eye.
The projects was set up to fund closer links between the University of Bath, UK, and the Indian Institute of Technology in Delhi. The £70,000 funding for it comes from these two institutions and from the UK India Education and Research Initiative (UKIERI).
The project will analyse the efficiency of a new thermography method developed in India, called Frequency Modulated Thermal Wave Imaging, in which the part being inspected is heated by shining light modulated over a range of frequencies onto it.
The technique is also called "chirp" modulation, as it was originally developed to improve radar performance and was later discovered to be used by bats to echo-locate using chirps of sound.
The researchers will compare this system to three other current thermography methods, which are being studied at University of Bath. If the new method is more effective, then the aircraft and other industries will be interested in using it.
"Composites have many advantages over metals, and it's not just small parts of aircraft that are being made from them now – entire wings are constructed from this type of material," said Professor Darryl Almond, of the Department of Mechanical Engineering, who will take charge of project, which begins in April.
"But composites are easily damaged in a way that isn't obvious to the eye, so regular safety inspections are essential. Thermography offers a way of doing this rapidly, so anything that improves the effectiveness of the technique is welcome."
Professor Almond, who is Director of the University's Materials Research Centre, recently won the Roy Sharpe prize from the British Institute of Non-Destructive Testing for his work in this area.
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