Frictional Behavior of Low-Cost Steel-Polymer Interfaces for Seismic Isolation

Abstract

This paper presents the results of an experimental program studying and comparing the frictional behavior of eight different polymers sliding on galvanized steel at velocities up to 350 mm/s, under a normal average pressure of approximately 18 MPa. This work focuses on how the coefficient of friction varies as a function of the instantaneous sliding velocity. We used a new type of testing apparatus together with novel loading protocols to study instantaneous values of the coefficient of friction, as opposed to values at peak velocities as typically done in past studies. The data collected in this study allowed a much better examination of the transient increase in frictional force that occurs at motion reversals due to stick-slip. Once the stick-slip effect has subsided, the relationship between the dynamic coefficient of friction and the instantaneous sliding velocity is described very accurately with a logarithmic model. Results from this study indicate that polyethylenes, which cost 5–10 times less than polytetrafluoroethylene (PTFE), sliding on galvanized steel, which costs about a third as much as mirror-finish stainless steel, have similar coefficients of friction to PTFE sliding on stainless steel at high velocities while showing significantly less signs of wear but have a more pronounced stick-slip effect. These findings suggest that seismic isolation may be economically feasible for use in low-rise residential construction by using polyethylenes sliding on galvanized steel.