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Changing Shapes

Graduate student Aaron Stebner finds a home for his research—and a passion in the classroom

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Aaron StebnerWhen Aaron Stebner was growing up near Akron, Ohio, the letters “EDC” stood for Electric Device Corporation. This company, started by his grandfather, a World War II veteran and self-taught engineer, manufactured automated test and manufacturing equipment for the circuit breaker industry. It also sparked Stebner’s interest in engineering.

“My grandfather used to take me to work when I was little. He’d sit me down on a table with a pile of alligator clips, and I’d just build things,” Stebner recalls. “And my father used to do all kinds of projects with me around the house. My family was really my inspiration.”

These days the family business is gone; the company was sold in the 2000s. And the letters “EDC” now mean something very different for Stebner: Engineering Design and Communication, a two-quarter course sequence required of all McCormick freshmen. Stebner, a PhD fellow in mechanical engineering and an adjunct lecturer at the Segal Design Institute, has been teaching the course since 2009.

Stebner’s expertise is in shape memory alloys, a type of metal that can “memorize” a shape and return to it under some kind of stimulus, such as a change in applied load or temperature. These materials open up vast possibilities. At the simple end of the spectrum, picture a paper clip that, after being unbent, springs back to its original shape when heated. At the complex end, imagine self-healing armor for vehicles and humans, morphing aircraft that change shape depending on their speed and altitude, and artificial heart valves that can be deployed through a catheter instead of being implanted through open-heart surgery. All of these are shape memory alloy projects currently under development that Stebner has worked on.

Niti wire surfaceIt’s easy to understand why Stebner became intrigued.“I grew up on Transformers and Voltron, before the revivals,” Stebner says. “Shape memory alloys allow these childhood fantasies to become reality, only for purposes that better our society rather than for entertainment.”

While Stebner wanted to be an engineer from an early age—he started working in his family’s business during high school—there was a time when he almost called it quits. After a tumultuous few years pursuing his undergraduate degree in New York and Ohio, Stebner dropped out of school, moved to Pittsburgh, and started Deejaying and working in a nightclub. It didn’t last. “I realized you can’t just spend your life in a nightclub,” Stebner says. “When it becomes your job, it stops being fun.”

So he went back to school, finishing bachelor’s and master’s degrees at the University of Akron. Doors started opening for Stebner when he won a fellowship at the NASA Glenn Research Center in Cleveland. He began working with shape memory alloys for aerospace applications, an important area of research that could lead to lighter, more fuel-efficient aircraft.

“It was an incredible opportunity,” Stebner recalls. “I drew upon my education and experience from my family’s company to design and build new test equipment for NASA’s high-temperature shape memory alloy program. Then I got to use my equipment to develop brand new actuation devices for making aircraft structures change shape during flight.”

After receiving his master’s degree, Stebner accepted a job at TZ Inc., a Chicago-based start-up that made shape memory alloy–based latches and locks—devices that allow people to unlock their homes with their cell phones, for example. But it wasn’t long before Stebner set his sights on Northwestern. “I realized my desire to learn more about shape memory alloys was burning strongly, and I knew the best way to do that was to commit to a PhD program that employs some of the world’s best professors in the field, namely Cate Brinson, David Dunand, and Gregory Olson,” Stebner says, citing three McCormick faculty members active in the field.

Stebner’s opportunities at McCormick have been plentiful. He landed a spot in Brinson’s lab, where he has worked on aerospace, automotive, defense, and medical applications of shape memory alloys. He has benefitted from several Northwestern fellowships, including ones from the Predictive Science and Engineering Design Program and the Initiative for Sustainability and Energy at Northwestern, as well as a dissertation fellowship from the endowment of Toshio Mura, a professor emeritus of civil and environmental engineering and mechanical engineering who passed away in August 2009. “These programs have provided me the freedom to pursue many different research paths during my time here and to continue to collaborate with colleagues at Los Alamos National Lab, NASA, and Boeing,” Stebner says.

His adjunct position at the Segal Design Institute has allowed Stebner to branch out into teaching. “I came to Northwestern with seven years of industry experience,” Stebner says. “The courses in Segal, especially EDC, are structured so I can share my experiences with the students through hands-on design and product development for real clients.”

Rod-shaped memory alloyStebner’s EDC students have worked on a dozen shape memory alloy projects for client companies. In a project with Boeing and Dynalloy, a shape memory alloy supplier, students redesigned the mechanism that deploys oxygen masks when the cabin pressure drops in an airliner. Their shape memory alloy devices were 60 percent lighter than the air-powered actuator used on the Boeing 747 today; the design could save airlines $200,000 in fuel costs each year the plane is in service, the students found. Other projects have included owl- and hawk-shaped bird deterrents that flap their wings at random intervals so birds don’t get used to the commotion, and a jet engine vent that can cool itself off by opening and closing as needed.

In the process of teaching EDC, Stebner has shifted his goals. When he embarked on his PhD, he says, his dream was to return to NASA. After defending his dissertation this spring, Stebner hopes to move on to an assistant professorship at a university.

“The opportunity to get into the classroom and connect with students changed me,” Stebner says. “The privilege of watching students blossom and succeed—to have them come back and tell you that something you said one day in the classroom has influenced that success—warms my heart and brings me a fulfillment that I don’t get from research alone.”