BEHAVIOR OF SAND PARTICLES IN SAND-STEEL FRICTION

ABSTRACT This paper describes a method for observing the particle behavior near the interface in sand-steel friction tests. A friction testing apparatus was modified to allow the observation of sand particles. Close-up photographs were taken of the sand particles at specified timing in sand-steel friction tests. The change in particle coordinates gives the displacement of particles during the friction test. The sand-steel interface showed a small amount of sliding before the peak in the frictional resistance. The sand on a smooth steel surface slid without large shear deformation. The sand particles on a rough steel surface rolled as well as slipped along the interface. These movements caused the formation of a shear zone within the sand along a rough interface. The displacement of stacked aluminum frames provides approximate displacement of the sand particles. The relative displacement between the bottom frame and the steel specimen gives the sliding displacement at the sand-steel interface.