[SY-O6] Symposium O-6

[SY-O6] Modeling the plastic deformation of a metal crystal induced by contact with a rough rigid surface

Invited

^○Lucia Nicola^1,2 (1.Delft University of Technology, Netherlands, 2.University of Padova, Italy)

When rough bodies are pressed against each other, a small contact area has to support all the load. This is why plastic deformation occurs even at moderate nominal contact pressure. Although indentation of elastic bodies by self-affine rough indenters has been studied extensively, little attention has so far been devoted to plasticity. This is mostly because capturing plasticity as well as contact with a self-affine rough surface is computationally quite challanging. Here, we succeed in achieving this goal by using Green's function dislocation dynamics, a modeling technique that combines discrete dislocation plasticity (DDP) with Green's function molecular dynamics (GFMD). As usual in DDP, plasticity is studied by tracking the nucleation and glide of each dislocation in the metal crystal. The dislocation image fields are instead calculated with GFMD, which allows to describe the self-affine rough surface using wavelenghts spanning from 5 nanometers to 100 micrometers.

Simulations are performed varying various parameters of the surface roughness, including the Hurst exponent and the root-mean-square height. Results show that the plastic response is size-dependent. An important implication of the size-dependence is that, when bodies deform plastically, it is not possible to scale observables such as contact pressure and contact area with crystal size or root-mean-square height, as typically done for elastic contact problems.