Material Witness: Award-winning Ph.D. candidate plumbs the nature of high-tech composites

Back when she was on her high school varsity tennis squad, Sarah Stair could hardly have imagined that her love for the sport might lead her into an even deeper fascination with the hidden complexities of the stuff things are made of – a fascination that would earn her national recognition and spur her to seek academe's highest achievement.

These days, the Arlington, Texas, native is a first-year Ph.D. candidate in mechanical engineering just back from a prestigious summer internship at Sandia National Labs in Albuquerque. She has little time to swing a racket, but acknowledges the role tennis played in her decision to come to Baylor.

"I went to tennis camps when I was in high school, and that's what got me interested in coming to Baylor," she related. "It's what got me on campus and I saw what it was really like here. Plus, my dad went to Baylor when the engineering department was just starting. He was here a couple of years and then transferred closer to home."

Stair's father is a mechanical engineer with a major aerospace firm in the Arlington area, so after checking out some other options for a major, she enrolled in Baylor's School of Engineering and Computer Science. But like most students, she didn't take to any particular aspect of engineering right off. It was a now-retired Baylor professor who introduced her to what would become her passion.

"It was an internship with Dr. (Walter) Bradley. I had him for materials class and he let me know about an internship he had that summer. I ended up working with the scanning electron microscope for about half the summer and I just fell in love with materials and material science."

Dr. David Jack, another Baylor mechanical engineering professor who eventually would become her graduate advisor, had several materials research projects going on. One was for L-3 Communications, an international aerospace company with a large aircraft modification operation near Baylor's Waco campus. The company had asked Jack and Birkeland Current, a local technology consultancy, for help in developing a way of determining the makeup of aircraft parts made of composite materials without damaging them in the process.

"I talked to Dr. Jack about some of the projects he had going on, and one of them was the L-3 project; that really piqued my interest," Stair recalled. She soon went to work in Jack's Materials Characterization Laboratory in the Baylor Research and Innovation Collaborative discovery park. There she began learning to use ultrasound to reveal the structure of composite materials.

"We're focused on layered carbon fiber composites. Traditionally ultrasound has been used just to locate delaminations or other defects," she explained. "We want to take that technology and use it to determine what kind of fabric layer is present, how thick that layer is, as well as the orientation or angle of a layer, and do that for each layer in the stack. Once we have that information, we can use it to back-out the failure envelope of a manufactured part and compare it to how the part was designed to perform. It's kind of like quality control."

That is just the kind of information a repair facility or aftermarket supplier needs to have before making modifications or repairs. The system Stair and Jack are developing is designed specifically for use in real-world environments, on an aircraft in a hangar, for example. Their work has already resulted in one patent, and a number of others are in-process.

Light and strong, carbon fiber is extensively used in the aerospace and automotive industries, as well as in many consumer items – like tennis rackets. The material's versatility makes Stair's research especially timely, drawing broad interest – and accolades – to her work.

She has received multiple awards from the Society of Plastics Engineers and the American Society of Mechanical Engineers, and this year Stair was granted a coveted Graduate Research Fellowship from the National Science Foundation. It was recognition that played no small part in landing her the Sandia internship. She beams when asked about the experience.

"It was wonderful. All the people that I worked with out there were wonderful. They were kind and welcoming and I learned something from every single person along the way. They are a very close-knit group," she recalled. The internship also gave her a larger perspective on research.

"Up until now I haven't had much business experience outside of Baylor. Sandia gave me more of a feel of what research would be like in a company environment. Now I have experience on both the academic and corporate sides."

As her graduate advisor, Jack says one of the things that makes Stair such an exceptional researcher is that her abilities are equally balanced.

"Not only is she good in the lab, but she's good on the theoretical side of things. She's good on what a lot of people consider the drudgery work," Jack said. "She somehow does it with such a positive attitude that it doesn't look like drudgery."

That may be true, but Stair is quick to give her mentor credit for that attribute.

"I try to balance the computational side with the experimental side, and that's something not a lot of people tend to do. But Dr. Jack actually has encouraged this. He likes to have that balance between the two," she said.

But make no mistake: given a choice, she's definitely a get-your-hands-dirty kind of researcher.

"You can ask the people I work with: when I go into the lab, I'm having a good day. I love to spend time in there working, making more materials, working with the systems, seeing if I can make it a little bit better, running different scans to have more data to analyze," she said. But her affinity for lab work surprised even herself. "I enjoy coming back to the computer and analyzing the data, but lab work is definitely something I didn't realize I would love so much."

Now settled in back at Baylor, Stair is eager to pursue her doctorate.

"I'm looking forward to getting back to research. That's a lot of fun. I got to do a lot of that this summer, and I'm just looking forward to continuing with that," she said.

Asked why she finds materials science so alluring, she replies with characteristic passion.

"Everything is made up of some kind of material and it's amazing to discover all the differences in things we use in our day-to-day lives. Contributing to that kind of research is exciting."

ABOUT BAYLOR UNIVERSITY
Baylor University is a private Christian university and a nationally ranked research institution, characterized as having “high research activity” by the Carnegie Foundation for the Advancement of Teaching. The university provides a vibrant campus community for approximately 15,000 students by blending interdisciplinary research with an international reputation for educational excellence and a faculty commitment to teaching and scholarship. Chartered in 1845 by the Republic of Texas through the efforts of Baptist pioneers, Baylor is the oldest continually operating university in Texas. Located in Waco, Baylor welcomes students from all 50 states and more than 80 countries to study a broad range of degrees among its 11 nationally recognized academic divisions. Baylor sponsors 19 varsity athletic teams and is a founding member of the Big 12 Conference.