I just finished up a really great interview with Aaron Stebner, a PhD fellow here at Northwestern. He's an expert on shape memory alloys (SMAs) - a combination of metals (alloy) that together have shape memory behaviors. Basically, you can manipulate and stretch the alloy, but once a certain stimulus is applied, like heat, it resumes its memorized shape. They're being used in medical devices, like orthodontic wires, and in components of cars and even airplanes. For those of us who have imagined semis transforming into superheroes since our childhood, this is one exciting prospect. But let's not get carried away. To get the full scoop on SMAs and their current (and future!) applications, check out the full interview.
Here, I'd like to share two videos with you that Aaron was kind enough to share with me. The first demonstrates SMA behavior. It shows two SMA wires that have been stretched out of shape, submerged in water. During the video, the water is heated up, and you can see them go back to their original shapes.
In the next video, we get to see a potential SMA application in action. Students in Aaron's undergraduate engineering design course (Jake VanderPloeg, Frank Cummins, Ben Woldenberg, Michael Chen, Evan Hunt, Lyndon Sapozhnik, Gregory Budd) redesigned the mechanism that releases oxygen masks during an emergency on 747 planes. You'll see one of the students touching a wire to the device, which applies a current, warming the SMA and causing it to regain its original shape, thus releasing the mask. The students, who had never seen an SMA before the class, were able to design the prototype in just a ten-week quarter. It weighs 70% less than the latch-and-release mechanism currently used in the 747 (just one advantage of SMAs). As we all know, less weight equals cost savings for the airline.
Want to learn more about SMAs and the other innovations they're inspiring? Aaron will give a Junior Science Cafe (open to middle and high school students and their families and teachers, free of charge), "Morphing Aircraft (and Other Cool Transformers)" on Friday January 21. Click here for more info.