Students from Aerospace Engineering have reached the second level of the Airbus competition “Fly Your Idea”. They propose to integrate sensors in tomorrow’s composites.
No shortage of interest for Airbus’ yearly mind-picking contest. Over 600 student teams from all over the world pitched their ideas in the open first round of the competition. Of these 100 teams were selected for the second round. Three of them are from the Netherlands: the Sit Tall team from InHolland University in Haarlem wants to improve seatbacks, team H2O (also from InHolland) aims to reduce water consumption on board and the TU Delft team Composite Future.
Composite Future team members Bram Davids, Philippe Willems and Maarten Debrouwere from Aerospace Engineering propose to integrate stress and delamination sensors into composite materials for aircraft hulls. This should allow for real-time structural insight as well as weight reductions.
Davids says he has floated the idea before. Last year, he pitched the same notion for the Space for Innovation competition. As it wasn’t picked up then, he recycled their work in the FYI-2012 competition, with better results.
Their idea is to integrate specially prepared glass fibers in fibrous layers of composite material. These fibers are sensitive to tensile strain and temperature due to a Fiber Bragg Grating. A network of intersecting fibers should allow not only for strain measurement, but also of localization.
Fiber Bragg grating works with a number of treated bands in a glass fiber. As light propagates along the fiber, a very narrow range of wavelengths is reflected by the (Bragg) grating, while all other wavelengths are transmitted. The smallest deformation of the fiber results in a shift of the Bragg frequency. Based on this principle Fiber Bragg grating sensors are in use as strain gauges in civil structures and aircraft, but also as pressure and temperature sensors in geological measurements.
Their academic mentor Dr Roger Groves (AE) says the technology was discovered in the 1990’s, after which a number of generic patents were issued for the use in strain and temperature sensing. The students’ proposal goes further than that, he says. They’re proposing an integral design to make a network of sensors and to develop a detection system that is fast and sensitive enough to deliver information about the damage in a composite structure. Next, they’ll be making a demo as a proof of principle.
Next to the glass fibers, the students want to make use of piezo-electric sensors as well. Tiny as they are (5 millimeter across and half a millimeter thick), their sensitivity to vibrations may sense when laminates detach.
An integrated network of built-in sensors that provides early warning for micro-cracks and delamination, may reduce both maintenance and weight, says Groves. If the sensors spot micro cracks before the inspection does, it may render it obsolete. And once damages are detected earlier, the composites don’t need to be over dimensioned quite as much and may be made lighter than at present.
Team Composite Future is looking forward to the end of April, when the finalists will be made public. These five teams have the privilege of pitching their idea for an Airbus jury in Hamburg. Follow the competition on: www.airbus-fyi.com
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