Computational investigation of slip rate dependent friction as a potential contribution to displacement bursts in nanoindentation of nickel

When nanoindentation is used for material characterization in small indentation depths, surface roughness and frictional effects can play an important role. In the present computational study the implications of a slip rate dependent frictional behavior in the tip-flat/rough sample contact are investigated. A potential contribution of stick–slip phenomenon generated/enhanced by the adopted velocity-weakening friction approximation to pop-in like displacement bursts is observed. Undoubtedly discrete plastic events are the dominant source of pop-ins in a general setting, however the investigated frictional effect is shown to give a potential contribution to experimentally observed nanoindentation displacement bursts in the studied setup.