Can the world of things be programmed the same way as a computer? When Skylar Tibbits, Director of the Self Assembly Lab at the Massachusetts Institute of Technology, talks about his work, it certainly sounds that way . And it actually works, at the micro and nano levels. He and other researchers use this to develop materials that respond in specific ways to specific environmental factors. These responses can be useful for human purposes. That’s why we call these materials "smart," and what makes them so interesting for virtually all industries. They can be used to replace environmentally harmful substances, reduce weight and cut energy consumption, and even to harvest energy in places where it has never been considered possible.
Shape memory alloys straighten out the world
Shape memory alloys are smart materials with lots of potential. They can be used for many different purposes – for example, cooling . The worldwide demand for cooling is rising due to climate change and growing population. That is expensive, and it burdens the atmosphere with greenhouse gases as well as enormous amounts of carbon dioxide from high electricity consumption, which also drives global warming. Research teams at the University of Saarland and Ruhr University Bochum are developing a cooling method with lower environmental impact using artificial muscles made from shape memory alloys. Their method does not need environmentally harmful refrigerants and is expected to consume less energy than conventional cooling methods. "We use systems with shape memory alloys to take away heat", says Stefan Seelecke, Professor of Smart Material Systems. Wires or metal sheets made from nickel-titanium alloy have a sort of memory capacity. If they are deformed, they return to their original shape when released. This allows them to tense up and relax like muscles. They absorb and release heat in the process, and the researchers use this effect to build their alternative cooling system.
Shape memory alloys can also absorb energy in other ways – for example, by converting energy into motion. Researchers are utilizing this property in "smart wings" for aircraft. A few months ago NASA scientists carried out a series of test flights with morphing wing technology , which is based on structures made from shape memory alloys . This enables the construction of hingeless flaps, leading to major reductions in weight, fuel costs and noise levels during takeoff and landing. This technology can also be used to optimize wind turbines.
Good vibrations: how smart materials could revolutionize electricity generation
Aircraft wings can also be used as a platform for materials that harvest energy from the environment – such as piezoelectric materials, which generate electricity when they are deformed. Four young scientists from Great Britain, the Netherlands, India and the USA have submitted an idea to the Airbus Fly Your Ideas contest for using piezoelectric materials to harvest energy from the natural vibrations of aircraft wings during flight. They propose covering the wings with a composite material containing embedded piezoelectric fibers. These fibers would convert even minute vibrations into electricity. This electricity could be stored in battery panels in the wings. The idea is to use this energy to power onboard systems such as the entertainment system or cabin lighting. This would reduce the energy consumption of the aircraft during flight and could even provide all the power necessary for ground operation, eliminating the need for an external power source.
This technology could also be used in many smaller, everyday devices. Early this year, a research group at the National Institute of Applied Sciences in Lyon (France) achieved a major breakthrough in electrostrictive polymers . Energy harvesting is much more effective with these materials, opening the door to a tantalizing application: replacing the batteries in virtually all mobile electronic devices.
Learn about the latest trends at the Special Exhibition on Innovative Materials in Lightweight Construction or in stimulating presentations by international experts on subjects such as Innovations in Applied Materials Research on 26 April 2016 at 11am in Hall 3, Stand F06/30-32.