Modelling surface roughening during plastic deformation of metal crystals under contact shear loading

Abstract

During plastic deformation, metal surfaces roughen and this has a deleterious impact on their tribological performance. It is therefore desirable to be able to predict and control the amount of roughening caused by subsurface plasticity. As a first step, we focus on modelling plastic deformation during contact shearing of an FCC metallic single crystal, employing a finite strain Discrete Dislocation Plasticity (DDP) formulation. This formulation allows us to capture the finite lattice rotations induced in the material by shearing and the corresponding local rotation of the crystallographic slip planes. The simulations predict a pronounced material pileup in front of the contact and a sink-in at its rear, which are strongly crystal-orientation dependent. By comparing finite and small strain DDP, we can assess the effect of slip plane rotation on surface roughening and on metal plasticity in general. Results of the simulations are also compared with crystal plasticity, which is also capable of predicting a pileup and sink-in, but not the crystal-orientation dependency of roughening.

On the Origin of Plastic Deformation and Surface Evolution in Nano-Fretting: A Discrete Dislocation Plasticity Analysis

“…Deshpande and co-workers [ 21 , 33 ] performed monotonic micro-sliding discrete dislocation plasticity (DDP) simulations to investigate the dislocation structure and surface behaviour under sliding. Nicola and co-workers [ 34 , 35 , 36 ] have also employed the DDP framework to understand the activity of dislocations under multi-asperity, self-affine contact, and the roughness (i.e., the height of the asperities) has been shown to play a key role in the development of plasticity in the subsurface. To the authors’ knowledge, there is no computational framework published for fretting fatigue using DDP.…”

Fluid Leakage in Metallic Seals

“…[27,28]. Several studies of surface roughness and plastic flow have been reported using microscopic (atomistic) models [29], or models inspired by atomic scale phenomena that control the nucleation and glide of the dislocations [30][31][32][33]. These models supply fundamental insight into the complex process of plastic flow, but are not easy to apply to practical systems involving inhomogeneous polycrystalline metals and alloys exhibiting surface roughness of many length scales.…”

Plastic Deformation of Rough Metallic Surfaces

“…Recently, several studies of surface roughness and plastic flow have been reported using microscopic (atomistic) models [32], or models inspired by atomic scale phenomena that control the nucleation and glide of the dislocations [33][34][35]. These models supply fundamental insight into the complex process of plastic flow, but are not easy to apply to practical systems involving inhomogeneous polycrystalline metals and alloys exhibiting surface roughness on many length scales.…”