Turning over a new leaf in manufacturing


Illustration by Brandan Deason

Proton exchange membrane fuel cells, or PEMs, hold promise as a clean energy source for transportation vehicles — from hybrid cars to future hypersonic spacecraft. But they aren’t yet as efficient at transferring energy as engineers would like.


Ming Leu, left, and Aaron Thornton, a Ph.D. student in mechanical engineering, with the freeze extrusion fabrication machine. Photo by B.A. Rupert

Some Missouri S&T engineers are looking to nature for inspiration.

By studying how the veins of a leaf carry nutrients from the stalk to the blade, these researchers hope to improve the way hydrogen flows through the PEMs. Analyzing leaf patterns from a variety of flora, the researchers are developing flow patterns to improve power density within the PEM cells.

This “bio-inspired” approach to manufacturing components is one example of the kind of advanced manufacturing research under way at Missouri S&T.

“We’re working to come up with new technologies, or to improve or optimize existing technologies,” says Ming C. Leu, the Keith and Pat Bailey Missouri Distinguished Professor of Integrated Product Manufacturing and director of S&T’s Center for Aerospace Manufacturing Technologies and the Intelligent Systems Center.

With the PEM fuel cell research, Leu and Umit Koylu, a professor of mechanical and aerospace engineering, are trying to improve an alternative energy technology. They’re using an additive manufacturing approach known as selective laser sintering, which uses a high-powered laser to fuse small particles of powdered materials — graphite composites, in the case of PEMs — to create 3-dimensional shapes, layer by layer.

S&T researchers can apply this high-tech sintering technique to other materials for other purposes. For instance, Leu and Greg Hilmas, Curators’ Professor of ceramic engineering, are selectively sintering special types of glass for biomedical applications and working with high-temperature ceramics that one day might be used to build hypersonic spacecraft.

As the White House pushes to create a National Network for Manufacturing Innovation to boost U.S. manufacturing competitiveness, Leu believes S&T is well-positioned for this new national agenda. He and his colleagues already work with industry partners to make manufacturing more efficient, less expensive and more innovative — all goals of the White House initiative.

For instance, Leu leads another additive manufacturing effort that holds promise for the nation’s aerospace industry. Working with Hilmas and Robert Landers, a professor of mechanical engineering, Leu is developing a process that mixes tough metals like tungsten with ceramic materials like zirconium carbide in a water-based slurry, then deposits the mix, layer by layer, in a pre-programmed model with “functionally graded materials.” The method could be used to create a nose cone that would allow spacecraft to withstand the extreme temperatures of high-speed space travel.

To carry out this research, Leu and his colleagues had to build a special computer-controlled machine with multiple extruders. They worked with Boeing Research and Technology to build the machine.
“This research is so new, there is no off-the-shelf technology available for us to use,” Leu says.

by Andrew Careaga

Learn more about mechanical and aerospace engineering at S&T.