October 16, 2020
Associate Professor Aaron Stebner joined the George W. Woodruff School of Mechanical Engineering this past summer and now that he has had some time to get situated and familiarize himself with Georgia Tech, it's time for the Woodruff School to become more familiar with him. Find out where he is from, how he got into his research field, who has had an influence on him, and more in this Q&A.
Where are you from and how did you end up at Georgia Tech?
Originally I’m from Ohio, between Cleveland and Youngstown. How did I end up at Tech? Before Georgia Tech, I was a professor at the Colorado School of Mines. I knew some people at Tech and they came out to visit and we just informally had conversations about figuring out how to work together someday. Eventually those conversations grew into visiting Tech and giving a seminar and eventually it grew into a job. I’m excited about everything going on with the Advanced Manufacturing Pilot Facility, the GT Manufacturing Institute and the Novelis Innovation Hub. I work a lot in mechanics and manufacturing with structural materials and metals and these new growth opportunities at Tech were exciting for me and were a big part of what drew me here.
Why did you choose a career in academia?
At first I didn't. I started out in engineering through a job in high school. My family had a circuit breaker manufacturing equipment business and I worked in the stock room then moved into assembly and up into engineering. One day, I decided that I didn't want to work in engineering anymore and I quit. I DJ’d for a few years and then decided I liked having a steady income a little better. I decided to go back into engineering and finished my bachelor's degree. I ended up doing a little bit of undergraduate research before I graduated and was offered Research Assistantship funding to pursue a master’s degree. I then won a NASA Graduate Student Research Program fellowship that supported the rest of my master’s degree, and I was introduced to shape memory alloy research through that experience.
After I finished my master’s degree I worked for a startup company in Chicago. The startup company was using shape memory alloy technology. After a year or so, I realized that I wanted to know more. I asked the company to pay for me to go back and pursue a PhD. When I started pursuing my PhD it wasn't because I wanted to be in academia, but I started teaching some and really liked it. Then I realized that I had been in industry a couple of times and quit after a couple of years each time. I knew I really liked teaching and research and decided to give academia a try and it's been a good balance of it all. If I get bored I can reinvent myself every year or two just by writing a grant on a different topic. When working for a company you’re always focused on one technology until you leave, so I think the ability to do new things every few years and not necessarily quit the old ones has kept me in academia.
Is there anyone that has had an influence on your career?
Yes, the first person is my grandfather who was a self-taught engineer. He did end up going back and earning a bachelor's degree after World War II while he was working. When I was a kid I would spend a couple of weeks in the summer with my grandparents. My grandfather would take me to work with him every day. One day he would set me up at a drafting board and the next day he’d hand me boxes of alligator clips and a power supply and let me zap myself and make little circuits. That's what really inspired me, he was the biggest influence on my decision to go into engineering.
Professor Dane Quinn (a Georgia Tech alumn) at the University of Akron also had an influence on my career. I did my undergrad research with him and he was the one that got me to think about graduate school and research. He encouraged me to apply for graduate fellowships and I won one at NASA and really would not have been able to do that without his encouragement and suggestions. Then, my NASA research advisors Drs. Santo Padula, Ron Noebe, and Dexter Johnson showed me how to immerse myself into a research problem – they introduced me to shape memory alloys, which are still at the core of the problems I study today. Ron is still one of my closest mentors and collaborators.
Finally, my PhD advisor, Cate Brinson influenced my career. She was the one that convinced me to try sticking with academia and helped me realize how much I liked teaching. My post-doc advisors G. Ravichandran and Kaushik Bhattacharya at Caltech have also been super influential with where I ended up going, my research ideas and how to approach the day to day job.
What classes will you be teaching?
I’ll be working on graduate coursework that brings together machine learning, manufacturing, and materials. I’m also excited to teach my engineering with shape memory alloys course at GT, which is a combined graduate and undergraduate course that combines mechanical engineering with materials engineering. I run the course in coordination with an international design competition for students on either designing or engineering new shape memory alloys for a specific application, so tailoring the temperature or the stresses at which they do their shape memory behavior by changing their chemistry or their processing. For the engineering students it may be designing an application that uses shape memory alloys for the motors, dampers, switches in devices- those kinds of things. The projects are sponsored by industry partners typically so students get to work with industry folks and there's a big competition, usually following the spring semester. There is also an international conference held every two years and I raise money for students to travel to the conference and present their designs.
What is your research area?
I started my graduate research in mechanics and thermodynamics of shape-memory alloys. For my master’s degree I was working at NASA and morphing aircraft structures. I was contributing to projects focused on making plane wings change shape, and using shape-memory alloys on turbine shrouds to keep a constant gap between the blade and the shroud, and applications like that. I got into biomedical applications, such as artificial heart valve frames and stents, towards the end of my PhD. I then started branching out into all kinds of areas of mechanics. My post doc focused on high-rate deformation and shock physics of structural metals, and then more recently, and I think the reason Georgia Tech was really excited to have me here, 3D printing metals and also integrating machine learning with mechanical behavior and manufacturing technologies. I think Dr. Graham and others are looking for me to develop a course around machine learning for mechanical/materials engineering. On the research side most of my research funding these days is in 3D printing metals or machine learning for 3D printing metals projects.
How did you end up getting interested in that particular field?
I got interested just by being open to it. When I applied for a NASA graduate fellowship as a master’s student, I didn’t even know what a shape memory alloy was. I wasn’t doing mechanics at the time, instead I was doing nonlinear dynamics work on resonance capture phenomena. I was more on the very edge of engineering and applied mathematics, but when I was interviewing onsite for NASA they asked me what I wanted to do, and at that time I liked solving all different kinds of problems. I’m open to any problem as long as it’s a good mathematical challenge and ideally a mechanical engineering challenge. At that time NASA’s metallurgy group had been developing these new high temperature shape-memory alloys and they were looking for collaborations in the mechanics and life group to be able to make structures. I just took that as my masters project, we had taken theses new high temperature alloys that had been characterized metallurgically and figured out how they behaved when made into spring geometries, tube geometries, wire geometries and different structural forms and how that interaction worked. That experience is what got started and then it kind of spring boarded from there.
Within academia, some people spend more time on the theoretical side and others focus on the application side. Where would you place yourself on that spectrum?
I would say that what makes my research lab unique is that we focus on being that bridge from basic science to application. We do fundamental things like in situ x-ray diffraction and neutron diffraction measurements where you have to know some pretty basic physics of scattering and particle interactions and basic science funding supports those types of projects. When we do those experiments we typically design them with the end goal of making better models for application design and that's really been a strength of our group over the years. We do basic things but we also have parts, 3D printed parts, driving around on military vehicles getting road tested this year, and we’ve also made the model that medical companies are using for their FDA qualifications of new artificial heart valves. We don’t just leave it at the publication typically- we file patents, create software and tools out of the knowledge we get from the basic science side and then computational vs. theoretical vs. experimental, we tend to be about half and half, maybe a little heavier, on experiments, but if we're doing an experiment often times we’re also developing a new theory for analyzing the data out of that experiment in a way that hasn’t been done before. Very few of my projects are either computational or an experiment- a lot of them involve a mixture of these things.
What are some of the projects that you are going to be working on in your lab at Georgia Tech?
The first project where I'm hiring students right away would be 3D printing of shape-memory alloys. I've had a lot of powders made of alloys that I've developed together with NASA collaborators that we believe are going to be better for 3D printing than the traditional shape-memory alloys. I have a master’s student finishing at Colorado School of Mines but I’m really excited to get a PhD student or two going here at Georgia Tech. I’d ideally like to hire one in materials that works more on structure property relationships, heat treatments, and more the metallurgy and then one in mechanical engineering that works more on the manufacturing, the process maps, how we process parameters out. Can we increase the processing space in different machines? How do they behave? That’s what I’m doubling down on as my startup projects. In addition it looks like we’ll have projects coming in for qualification of 3D printed metal parts using data informatics and a project for machine learning on alloy design databases with NASA, so it there should be other opportunities in those spaces as well.
Is there anything that you’ve learned so far as a professor on how to build a good lab environment and lab community?
I think it's important to remember the social aspect of the lab environment, which of course is a real challenge in these Covid-19 times. I make sure that there's at least one conference every year where everybody in the research group goes, even if it's not necessarily the best conference for their topic. We tend to create a group identity when we go to say a TMS conference or an ASME conference. When our whole group is there we bond differently in that environment than we do day-to-day in the lab. We also try to have at least three or four social events for the group each semester. Some of our in situ x-ray and neutron experiments we conduct happen at national labs on their equipment and the experiments run for 24 hours a day, five or six days in a row, so we usually need five or six people to staff it and support it, so we send a group of people.
In general I would say our group tends to be a pretty collaborative group and social group. If someone wants to just come and crank out calculations and go home every day it’s probably not a great group for them. I think there's a heavy emphasis in my group on networking and social and professional development just as much as there is on learning the basics and being able to do research and that tends to be our environment.
What's the biggest challenge in being a new professor on campus?
Covid-19 is creating its own set of challenges but I would say the biggest challenge would be getting that first grant in. As a brand new professor at Mines, I got a verbal notification of my first grant but then it took 20 months to get through the contract process, so it ended up stringing out a year and a half almost. In fact my second grant came before the first contractually. I think in this stage of my career that's not as big of a concern, these things are more rolling, but I would say the finances are always stressful and people depend on you for paychecks and paying for their education, so getting that going and in order, getting a good base set up again, was probably one of the biggest inhibitors to moving. There's a nice financial base still sitting at Colorado School of Mines for the students that are still there but getting that going again at Georgia Tech will be a big part of my focus the first year and one of the more nerve-wracking things to set up. Otherwise just learning the ropes – I got very comfortable after spending seven years in at one institution and now, even though I came from one engineering school to another engineering school, I’m still finding a lot of things are different and its harder this time than the first time. I knew I didn’t know a lot the first time, so I asked about everything. Now I think I know how to do everything because I’ve been doing it for seven years and I find out I didn't ask the right person or do it the right way, so I need to step back and admit I don’t know anything again and that's maybe one of the harder things.
What do you like to do when you’re away from work?
I like working on my house and renovating or refinishing furniture. I also enjoy spending time with my kids, which is what I mostly do, and the things that they’re into. Fly fishing is something else I tend to do when I can.