Research Needs and Opportunities in the Area of Friction and System Dynamics – Part II

Heshmat, H. et al. “Research Needs and Opportunities in the Area of Friction and System Dynamics – Part II,” ASME Report No. CRTD-48, Proceeding of the Workshop on the Interaction of Friction and System Dynamics, Edited by A. Akay and A. Gellman, Sponsored by The NSF, June 20-23, 1997.

A wide variety of friction related phenomena at sliding interfaces influence the dynamical response of mechanical systems.  the understanding of these phenomena and their coupling to mechanical assemblies are poorly understood and yet have enormous consequences.  A workshop held over the period June 20-23, 1997 defined a number of microscopic interfacial phenomena that contribute to these large scale dynamic responses.  These phenomena themselves are not completely understood, however, by developing a microscopic understanding and theory that can be scaled up to the macroscopic level it was felt that global models could be developed for predicting the effects of friction in moving mechanical assemblies.  It was recognized that as an important element of the scale-up one must consider both the influence of friction on system dynamics and the effect of system dynamics on friction.  Empirically-based models are considered to be useful for the range of parameters over which they are obtained and, generally, may not be extrapolated to outside of their range.  Further difficulty with empirical models is associated with repeatability of measurements which, in part, stems from dynamic behavior of the measurement set ups.  These issues were discussed in the specific context of brake applications and a series of recommendations were made concerning the type and level of modeling that is needed to further our understanding of the coupling between friction and system dynamics.