Perpustakaan Digital ITB

Multiscale simulations of the tilted flat-ended nanoindentation with different tilted angles (from 5? 30?) on the (?1 1 0) surface of nickel crystal were studied using the QC method. The model of the indentation is a flat-end indenter inclined by an angle " driven into a half- plane vertically. Load-displacement responses, initial stages of the plasticity deformations and dislocation emissions for nickel film at different inclined angles were obtained and analyzed as well. An energy criterion was successfully proposed to analyze the critical load for the first dislocation emission beneath the edge of the indenter. Simulation results agree well with analytical ones. An elastic model based on the contact theory and the Peierls-Nabarro dislocation model were combined to analyze when and where the dislocation will be emitted beneath the lower surface of an inclined indenter. Results indicate that the key parameter is the ratio of the contact half- width to the position of the slip plane. This parameter shows the range in which a dislocation will probably be emitted. This mechanism explains the simulation results well. This work is of value for understanding the mechanism of dislocation emissions of FCC crystals under tilted flat- ended nanoindentation while providing approaches to predicting when the first dislocation will be emitted and where subsequent dislocations will probably be emitted.