Dynamics of static friction between steel and silicon
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Communicated by Harry L. Swinney, University of Texas, Austin, TX, June 28, 2008 (received for review February 4, 2008)
Abstract
We conducted experiments in which steel and silicon or quartz are clamped together. Even with the smallest tangential forces we could apply, we always found reproducible sliding motions on the nanometer scale. The velocities we study are thousands of times smaller than in previous investigations. The samples first slide and then lock up even when external forces hold steady. One might call the result “slip-stick” friction. We account for the results with a phenomenological theory that results from considering the rate and state theory of dynamic friction at low velocities. Our measurements lead us to set the instantaneous coefficient of static friction that normally enters rate and state theories to zero.
Footnotes
- †To whom correspondence should be addressed. E-mail: marder{at}mail.utexas.edu
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Author contributions: Z.Y., H.P.Z., and M.M. designed research; Z.Y. performed research; Z.Y. and M.M. analyzed data; and H.P.Z. and M.M. wrote the paper.
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The authors declare no conflict of interest.
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See Commentary on page 13187.
- © 2008 by The National Academy of Sciences of the USA
