”Much of my research involves the use of smart materials in different ways,” says Professor Adam Wickenheiser of the Department of Mechanical and Aerospace Engineering. In fact, Wickenheiser began working with smart materials because he thinks they are the key to miniaturizing sensing and actuation technology.
Smart materials are multifunctional: they can be used both structurally, like concrete or steel, and for a secondary purpose, such as producing an electromagnetic signal or heat flux. Because they can perform two functions at once, they enable researchers like Wickenheiser to design small scale technologies that would not be possible with discrete components.
Wickenheiser’s primary research project uses smart materials to develop sensors and actuators for bird-scale aircraft, which are one- to two-foot, unmanned aircraft that may one day be used for monitoring or surveillance missions close to the ground or within cities. One of Wickenheiser’s big challenges is to design a wing that can respond effectively to turbulence and gusting, because as aircraft become smaller, the influence of wind disturbance becomes relatively larger.
To meet this challenge, he is looking for clues from bird wings. “If a large gust of wind hits a bird, its wings have a certain amount of passive flexibility, and the feathers deflect in response, without the bird really making a conscious decision,” says Wickenheiser. “We’re trying to build a closed loop feedback system into the model wing itself, so it can detect a disturbance and then respond more automatically, like a bird’s wing.”
Wickenheiser believes that his background gives him a somewhat unique advantage in trying to solve this problem. “Because I have a background in smart materials and fluid mechanics and control systems, I’m looking at this from a multi-physics perspective. I’m looking at the fluids and the structure and electrical circuit together to see how they combine to give an efficient design,” he remarks.
So far, he and his team have developed a model of a wing section with feather panels and have run a multi-physics simulation of it passing through turbulence. After validating the simulations, they will compare their results with experimental results from a model they will test in a wind tunnel. The feedback mechanism on the system they are creating is designed such that the wing panel can monitor itself in real time and adjust its response to the changes in turbulence set by the team.
In Wickenheiser’s view, this ability is a game-changer. “The reason we’re going through all of this is that simulations can’t be done in real time,” he says. “A single simulation can take hours or days depending on its complexity. But we’ve outfitted our system with enough sensing and feedback capability that it basically will be able to monitor itself and learn from what it’s doing. Once we have that in place, I think that the speed at which we’ll be able to develop new results is going to be light years ahead of what we’re able to do in simulation.” He adds, “And as far as I know no one else is doing anything as extensive as this using active wings.”