Experimental study on the static rolling friction coefficient of a flat-roller-flat configuration considering surface roughness

Abstract

The friction-based seismic isolation technology is widely used in structural engineering. Despite the advantages and disadvantages of different types of isolated bearings, the coefficient of friction is a crucial factor that affects the seismic performance and stability of the isolation systems. In this study, a test apparatus with a flat-roller-flat configuration is developed to measure the static rolling friction coefficient (SRFC) of roller shafts. The SRFC under different conditions of normal load, material properties, geometry characteristics, and surface roughness are experimentally studied. The SRFC of the aluminum roller shafts ranges between 0.0020 and 0.0150, while that of the acrylic roller shaft ranges between 0.0028 and 0.0177, under low normal load level. The SRFCs of the roller shafts are positively correlated with the normal load and negatively correlated with their diameters. The surface roughness of the bottom plate significantly affects the SRFC. More precisely, the larger the surface roughness, the larger the SRFC. A theoretical model based on the elastic hysteresis theory is also proposed to predicted the SRFC. It is assumed that the elastic hysteresis loss coefficient (EHLC) is linearly correlated with the surface roughness of the bottom plate. Compared with the experimental results, the values predicted theoretically are within the error of 25 % for 85 % cases.