Normal Contact Analysis Between Two Self-affine Fractal Surfaces at the Nanoscale by Molecular Dynamics Simulations

This work attempts to investigate contact between two self-affine fractal surfaces with one being of a rigid solid and other of a FCC deformable body. A normal contact model between two self-affine fractal surfaces at the nanoscale is established. Effects of surface morphology on contact force, atomic structure, dislocation with normal displacement are investigated by simulating the contact process of self-affine surfaces. Results show that the normal force for rougher surfaces at initial contact yields the larger negative extremum due to effects of surface morphology on interatomic repulsion and attraction. Furthermore, the atomic structure change proportion varies monotonically with normal displacement whereas effects of surface morphology can be approximately ignored. However, the phase transition generated by too large atomic slip leads to a non-monotonic variation between total dislocation lines length and normal displacement. Differences in contact ratio-separation dependence between the classical micro-asperity model and the established model are compared. (GRAPHICS)