Senior mechanical engineering major Ben Blume presented his poster on the thermomechanical analysis of large format printed polymer composite structures at the North American Thermal Analysis Symposium, which was held in Knoxville in September.
Blume’s poster was part of his undergraduate research in the lab of Professor Chad Duty under PhD student Tyler Corum. The project is in partnership with Oak Ridge National Laboratory.
“It was a lot of fun. I was around a lot of professionals who live and breathe thermomechanical analysis, so it was cool to see a lot of their posters and all the amazing work they’re doing,” Blume said. “There were a lot of people other colleges, as well as a few scientists from China whose posters were about thermal mechanical analysis of cigarette tobacco, which I didn’t know there was so much like background science behind that.”
Directional Differences
Large-format additive manufacturing (LFAM) is a method of manufacturing in which a structure is created in a layer-by-layer fashion by extruding material only where it’s required. LFAM was used in Blume’s project to create a fiber reinforced structure made from 20 percent carbon fiber reinforced acrylonitrile butadiene styrene.
“The whole purpose of printing carbon fiber ABS printed with LFAM is for autoclave tooling in the aerospace industry,” Blume said. “It’s important to know how the structure will shrink and grow when you heat it up so you can achieve the correct dimensions for your final product.”
Coefficient thermal expansion (CTE) is how much a material expands when it’s heated, which depends upon the material used. To characterize the CTE, Blume used thermal mechanical analysis with the TA Instruments Q400 thermomechanical analysis system.
“As you go across the cross section of a bead, you’re going to have different mechanical properties across the bead. That’s what’s called non-homogeneous microstructure,” Blume said. “Across the structure, you have different properties, and to better characterize that LFAM structure, I used discreet sampling across one bead.”
Blume cut samples into five-millimeter cubes and placed them underneath the Q400. He heated them up to 90 degrees Celsius and used a glass probe to measure how much it expanded as the temperature increased. Blume did this in three directions, x, y, and z. The CTE values were much lower in the x-direction as the carbon fiber reinforcement is orientated in that direction. However, the CTE values in the y and z direction were much higher as it was measured perpendicular to the aligned fibers. Because there was differing amounts of aligned carbon fibers in the different samples taken across one bead, the CTE values were non-homogeneous across the sampled bead.
“That was a curious thing we found—that in the y and z direction, CTE was inversely related, but they’re also not symmetric across the center of the bead, which was unexpected,” Blume said. “That was likely due to when you print it, one side is going to interact with the previously printed bead, while the other side is just going interact with air without any additional contact.”
Future Ambitions
The next step for the project is to put the CTE data into a finite element analysis model and then simulate tooling conditions. Blume plans to repeat the process with another LFAM printing system this semester.
“I feel I got a lot of self-worth out of this project, because I feel like this research is actually applicable to stuff, and that’s a nice feeling,” he said. “It’s not research just for research’s sake. It’s research for a purpose.”
Blume’s father was in the Army and his family moved around the country when he was young. He’s lived in Kentucky, Tennessee, Texas, and spent the first three years of high school living in Germany.
“It was a blast. I went an American-run high school on base, and I was part of the baseball team,” he said. “We would drive to other parts of Germany to play baseball, and we even drove all the way to the Italian Alps to go play baseball in Vicenza.”
Blume is on track to graduate with his degree in December and begin working with NAVAIR in Patuxent River, Maryland. He served an internship with the company last summer and will be returning to conduct non-destruction inspections of aircraft.
“Working with the Navy, I will have a lot of opportunities to travel,” Blume said. “There are naval bases all around the world and I should get a chance to explore different countries. I am looking forward to that.”
Contact
Rhiannon Potkey (865-974-0683, rpotkey@utk.edu)