Analysis of the Contact and Friction Force Behaviour between Different Indenter Shape and Substrate on Atomic Scale

On the conditions of considering the substrate elastic-plastic deformation and anisotropy of single crystal copper,the adhesive contact and frictional process of indenter (semi-spherical and conical) to the substrate were investigated by molecular dynamics simulation based on embedded atom potentials and verlet algorithm,and analyzed the influence of the contact and friction force on the failure of atoms in substrate. During the semi-spherical indenter moved down to 0.9 nm,the gravity between semi-spherical indenter and substrate became more lager than conical indenter,which resulted in the adhesive contact phenomenon happened easier than conical indenter because of the semi-spherical indenter's surface area is lager than conical indenter. At the same time,the dislocation loop grouped up and expanded as indentation depth increased for semi-spherical indenter in the indenting process,but not for conical indenter. During the process of sliding,the atoms ahead of the indenter accumulated gradually for the large friction and normal force of the semi-spherical indenter to the substrate,and the number of accumulated atoms in the above process is much larger than the atoms caused by conical indenter. Furthermore,because of the existence of adhesion and surface force,the number of residual atoms on the surface of the substrate contacted with a conical indenter is smaller than the one contacted with a semi-spherical indenter.