Smart alloys controlling aircraft wings
The shapes of modern aircraft wings are optimised for cruising flight. In other situations, especially during the slow speeds of takeoff and landing, aircraft wings are non-optimal and need considerable shape alteration. Traditionally, this has been achieved with heavy, hydraulically adjusted flight surfaces. A more advanced solution is smart materials, shape memory alloys (SMAs), which change shape on their own depending on physical conditions, including temperature. Such materials seem superior in every way to conventional hydraulic wing controls: lighter, simpler, cheaper and safer. They should be especially suitable as actuators — mechanisms that initiate other devices or actions. Not surprisingly, aviation and other industries are showing great interest in this technology. However, some technical problems remained. The EU-funded project, 'LE coupon based technology' (SMYLE), where LE stands for leading edge worked to address these problems. The project aimed to design, build and test high-performance actuators employing various SMA technologies. These will be specifically focused on morphing wing applications, giving expected significant improvements to wing aerodynamics. The devices will also have secondary application as de-icing systems, which should further save weight compared to conventional hydraulics. Most work to date has been preliminary, focusing on literature reviews and discussion regarding technical choices. Similarly, the driving theoretical models have been refined and finalised. Two different approaches to using SMAs as actuators have been compared, leading to trial systems now ready for testing. Results of experiments have been very promising, leading to the desired wing deformation being achieved in all cases. SMYLE has also developed an effective feedback-driven control system. Further work remains to be done, and this has been defined and scheduled. SMYLE disseminated its results as a paper presented at a smart materials conference in June 2013. Beyond aircraft control surfaces, the technology may also be applicable to other branches of aviation such as aircraft engines and diagnostics. This would lead to smaller components, meaning reduced weight and maintenance. SMAs may finally prove to be useful as morphing helicopter blades, and show promise for application in the shipbuilding and automotive industries as well.
