The science of friction
Burris awarded NSF grant to elucidate scaling effects in friction
8 a.m., Aug. 12, 2014--Friction helps us light fires in the wilderness, stop our cars at red lights, and run on pavement without slipping. It affects everything from cellular interactions to seismic activity.
“Friction governs the operating limitations, durability, energy consumption, and control of virtually all machines, including those with important implications for health care, economic prosperity, and national security,” says David Burris, assistant professor of mechanical engineering at the University of Delaware.
Learning from leeches
“Although we sense friction at the macroscale, it’s known to originate at the atomic scale,” he continues. “The scientific roots of this subject date back to Leonardo da Vinci, but our understanding of how these fundamental atomic-scale interactions contribute to everyday friction remains poor.”
Burris hopes to fill that basic gap in knowledge with a $300,000 grant from the National Science Foundation that will support a controlled study of interfacial friction from the atomic scale to the practical scale. The results will be used to develop a testable model of frictional scaling, which is needed to inform materials design and surface engineering efforts for friction control applications.
Burris, who is an expert in tribology, or the scientific study of friction, explains that although traditional tribometry allows us to measure friction at practical size-scales, it tells us almost nothing about the responsible phenomena and does not provide any insight into the design of new low friction materials.
“Although we understand that friction originates at the atomic scale, we lack the tools needed to quantitatively study how these interactions contribute to the generation of machine friction,” he says.
Burris and his research team have developed two key technologies to enable this project. The first is a method to reliably calibrate and quantitatively measure atomic-scale friction using atomic force microscopy, and the second is a microtribometer that can bridge measurements from the atomic scale to those from the macroscale.
“Our aim now is to stitch these length scales together by carefully controlling material, load, probe radius, and speed in the gap between the atomic and macro size scales,” Burris says.
“By making simple observations of friction across length scales, we hope to quantitatively link the friction we observe every day to its fundamental origins. Our long-term goal is to produce a testable theory of interfacial friction that our materials scientist collaborators can use to design materials and engineer interfaces for improved frictional control.”
Article by Diane Kukich