Behaviour of model abrasive particles between a sliding elastomer surface and a steel counterface

Wear at a sliding elastomer-steel interface may occur as a result of direct interaction but also as a result of intervening particles. Much previous w ork to study abrasion of elastomers has involved the use of blade abrader a rrangements. In the current work, a complementary approach is adopted; the short term and longer term motion of model particles (mild steel cylinders and hexagonal rods of steel and of quartz) has been modelled (by means of F inite Elements, FE) and studied experimentally. FE modelling supported by experiment has indicated that a cylindrical model particle rolls when between a sliding rubber block and a (dry) steel count erface. At low loads, the tangential velocity of the "particle" matches, wh ile at high loads, exceeds the velocity of the rubber block. For hexagonal model particles of steel and also of quartz, the particle ini tially slid on the (oxidised) steel counterface - the ratio of horizontal t o vertical force being low (approximate to 0.10-0.14). However, continued s liding produced clean metal surfaces and hence a coefficient of friction su fficiently high (approximate to 0.20-0.25) that incipient rolling of the pa rticle occurred between rubber block and steel counterface. A similar patte rn of behaviour was observed with a worn irregular particle of limestone. F or a sharp-edged irregular particle of quartz, however, rocking rather than sliding occurred immediately. FE analysis was successful in modelling roll ing of the hexagonal particle and in predicting the approximate (steel-part icle) frictional coefficient required for rolling to just occur - although the experimental values were somewhat lower. The findings suggest that a number of patterns of particle movement (and th us modes of stressing of the rubber) may occur in rubber where it slides ov er mild steel in the presence of abrasive particles (and oxygen); what mode of stressing occurs will depend, inter alia, on what type of abrasion occu rs at the particle-steel interface. (C) 2000 Elsevier Science S.A. All righ ts reserved.