An auxetic honeycomb that changes shape using piezo-electric actuators and other sensors embedded in each of the structure's cells could enable lightweight, power-efficient flexing control surfaces for morphing wings, say researchers. An auxetic material has a negative poisson ratio, meaning its cross-section becomes wider when stretched. The embedded sensors can enable health monitoring and honeycomb cell dimensions could be matched to incoming signals' wavelengths so the structure could, for example, reflect radar, absorb it or even allow it to pass through. Developed through the European Union's Sixth Framework programme's three-year €3 million ($4.2 million) chiral smart honeycomb project, it involved 10 organisations including the universities of Bristol, Malta, Exeter and the Frauenhoffer and Technion institutes. The project started in 2005.

Source: Flight International