Purdue News

From the summer 2003 edition of Purdue Engineering Extrapolations

Undergraduate Research

Fascinating friction

A lack of understanding of friction wastes an estimated $420 billion every year in the United States alone. Bill Conley, a senior in Purdue’s School of Mechanical Engineering, has been exploring the problem. His undergraduate research project seeks insight into atomic-scale friction. "It’s fun," says Conley with a wide grin.

Bill Conley
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It’s also a new direction for Arvind Raman and Charles Krousgrill, his mentors and professors in mechanical engineering who developed the project. Combining interests and expertise in physics and mechanics, they are studying nanoscale friction. They hope to determine how individual asperities–roughness on a surface–interact.

Their research, a detailed computational and analytical investigation of Tomlinson’s model for atomic-scale dry friction, has implications for how to structure the surface of material. "If you know what’s happening between two little points sticking up on a surface, the way they interact, and if you can control the surface and where those are going, you can control what the frictional properties between the two points are going to be," explains Conley. "Then you can scale it to an entire surface and pattern that surface to reduce friction."

By structuring the material at the nanoscale, it will be possible to alter the frictional properties at the macroscale. This nanoscale structuring will allow for designer frictional properties between surfaces.

Accurate modeling and control of dry friction are important in a number of technological applications, including space robots and satellites, hard disk drives, automobile disc brakes, MEMS (micro-electro-mechanical system) devices, nanoscale lithography, imaging, and data storage. The research in which Conley is involved demonstrates that the use of computational nonlinear dynamics techniques provides deep insight into the mechanisms of chaotic stick-slip phenomena and the speed dependence of frictional forces of atomic-scale friction.

"Even though I am an undergraduate, I attend weekly meetings of Professor Raman’s graduate students," says Conley. Every week a different student is called upon to present his or her latest research results. It’s like a class, but less formal. "We don’t know the answers," Conley adds. "We’re all learning as we go along."

Conley’s experience has given him a better understanding of the workings of a world-class research university. "I realize the impact of fundamental research now," he says. "I’m planning for a career in academia or at a government national research laboratory."

He also has a journal publication to his credit and has traveled to San Francisco to deliver a paper at the International Conference for Computational Nanotechnology. Conley’s research experience as an undergraduate has improved his chances to receive a graduate student fellowship, and even more important, has laid the groundwork for what he describes as "a dream career": the opportunity to study fascinating problems for the next 40 years. Says the Purdue senior, "I really like this stuff."

Writer: Mary Lundstrom

Photo: Vincent Walter