A Seamless Multi-scale Approach to Model Indentation of Metals

A seamless 2D dual-scale computational scheme is developed to study contact problems. The model consists of an atomistic domain close to the contact, coupled with an elastic continuum domain away from the contact. The atomistic formulation provides a description of the contact interaction through interatomic potentials and permits to capture atomic wear and defect formation in the contact region. The fields in the continuum domain are calculated by an efficient FFT-based Green's function method. The novel scheme is validated against full atomistic simulations and applied to study the effect of adhesion on the scratching of a rough copper surface by a rigid smooth spherical tip. A new interatomic function based on pairwise Morse potential is proposed to study the effect of adhesion on friction. It is found that increasing the maximum force and/or the cut-off distance of the potential leads to atomic wear. In addition the normal force acting on the indenter plays a role on the thresholds above which the wear initiates. By adding dislocation dynamics to the continuum domain, all the ingredients are put together to have a dual-scale scheme to properly simulate contact mechanics problems including plastic deformation. The dislocation transfer mechanism between the two domains is implemented and tested successfully.