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Ground-breaking results without breaking the plane

Smart or adaptive materials are those that sense and respond to changes in their local environment in a graded and appropriate way much as a biological system does. EU-funded researchers applied adaptive materials technology to aircraft landing gear culminating in a first-ever test flight demonstration of active shock absorbers.

Industrial Technologies

Piezo-electric and magneto-rheostatic (MR) materials are two types of smart materials currently being implemented in a variety of test and industrial applications. Piezo-electric materials reversibly change size in response to an electrical charge. MR fluids can reversibly change to nearly solid form within a fraction of a second when exposed to a magnetic field. The ‘Adaptive landing gears for improved impact absorption’ (Adland) project sought to develop and test new concepts using piezo-electric and MR materials in adaptive shock absorbers and active vibration dampers for aircraft landing gear. Currently, only passive systems are used, with their specifications and characteristics defined by the most frequently encountered loading conditions. However, due to the highly varying loads encountered on landing, the passive systems’ performance is often less than optimal. The researchers focused on active adaptation of energy absorbing structural elements, generally more reliable, stable and cost-effective than passive energy absorption. Specifically, they used sensors that evaluated potential impact in advance and produced a response in semi-controllable dissipaters that varied with the impending load. Active adaptation ensured that external energy requirements were minimised since actuators modified local forces rather than generating others. In summary, the researchers developed, characterised and predicted the response of new MR fluids, incorporating them in a full-scale MR fluid damping device. They also produced a piezo-electric damping valve shock absorber. Finally, they built a drop test facility employing the vibration damper and shock absorber, demonstrating fail-safe characteristics. The new MR damper demonstrated excellent controllability performance. Of particular importance, they conducted the first-ever flight test of a piezo-electric adaptive aircraft shock absorber. The Adland project outcomes are expected to have significant impact on design and safety in the aircraft industry as well as more generally in the field of impact absorption and vibration damping. The novel exploitation of adaptive materials for improved aircraft landing gear should provide a competitive edge to the European aerospace industry with positive effects for numerous others, boosting European safety standards and consumer confidence with important economic rewards.

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