MEchanics GAthering -MEGA- Seminar: Talk1 - Mechanisms of adhesive wear: A view from the nanoscale; Talk2 - Emergence of self-affine surfaces under adhesive three-body wear conditions
Event details
| Date | 07.03.2019 |
| Hour | 16:15 › 17:30 |
| Speaker | Tobias Brink & Enrico Milanes, LSMS, EPFL |
| Location | |
| Category | Conferences - Seminars |
Mechanisms of adhesive wear: A view from the nanoscale by Tobias Brink, LSMS, EPFL
Adhesive wear occurs in all sliding contacts as a result of the formation of local adhesive bonds between the surfaces. It is clear that material loss is due to the formation of loose wear particles, but the prediction of wear rates remains challenging, not least because the microscale mechanisms of wear are still poorly understood. Our research is currently centered around understanding the wear particle formation as a ductile-to-brittle transition, taking the geometry and material properties of contacting surface asperities into account. We use computer simulations to investigate the formation of these wear particles and their co-evolution with the surface for dry contacts. This talk will focus on molecular dynamics simulations of the onset of debris formation, which help us to untangle the influence of bulk and interface properties on different wear scenarios on the sub-micron scale. I will discuss how these wear mechanisms could potentially result in macroscopically observed wear phenomena and what open questions remain.
Emergence of self-affine surfaces under adhesive three-body wear conditions by Enrico Milanes, LSMS, EPFL
Wear of materials plays a key role in the durability of manufactured objects and has therefore an important economic impact. A unified picture of the physics of wear is nonetheless still missing, due to its high complexity: multiple phenomena take place at the interface of two rubbing surfaces (ductile and brittle deformation, adhesion, contact, etc.) which in turn affect one another and the overall frictional behaviour. In this second part of the seminar, we will focus on the surface roughness evolution of sliding surfaces with third-body formation. The study was conducted by means of long-timescale molecular dynamics simulations on simple 2D model systems. We show that surfaces do not smooth, rather reach a steady-state roughness and a self-affine morphology characterized by a persistent Hurst exponent. We ascribe this behaviour to the interplay between ductile and brittle deformation mechanisms, and to the presence of the third body. As no debris evacuation is allowed, our case most closely resembles the state in closed system, such as natural rock faults. The latter also display self-affine morphology with a persistent Hurst exponent. We will also address the main differences between a two-body and a three-body configuration in terms of wear volume and frictional work evolution.
Adhesive wear occurs in all sliding contacts as a result of the formation of local adhesive bonds between the surfaces. It is clear that material loss is due to the formation of loose wear particles, but the prediction of wear rates remains challenging, not least because the microscale mechanisms of wear are still poorly understood. Our research is currently centered around understanding the wear particle formation as a ductile-to-brittle transition, taking the geometry and material properties of contacting surface asperities into account. We use computer simulations to investigate the formation of these wear particles and their co-evolution with the surface for dry contacts. This talk will focus on molecular dynamics simulations of the onset of debris formation, which help us to untangle the influence of bulk and interface properties on different wear scenarios on the sub-micron scale. I will discuss how these wear mechanisms could potentially result in macroscopically observed wear phenomena and what open questions remain.
Emergence of self-affine surfaces under adhesive three-body wear conditions by Enrico Milanes, LSMS, EPFL
Wear of materials plays a key role in the durability of manufactured objects and has therefore an important economic impact. A unified picture of the physics of wear is nonetheless still missing, due to its high complexity: multiple phenomena take place at the interface of two rubbing surfaces (ductile and brittle deformation, adhesion, contact, etc.) which in turn affect one another and the overall frictional behaviour. In this second part of the seminar, we will focus on the surface roughness evolution of sliding surfaces with third-body formation. The study was conducted by means of long-timescale molecular dynamics simulations on simple 2D model systems. We show that surfaces do not smooth, rather reach a steady-state roughness and a self-affine morphology characterized by a persistent Hurst exponent. We ascribe this behaviour to the interplay between ductile and brittle deformation mechanisms, and to the presence of the third body. As no debris evacuation is allowed, our case most closely resembles the state in closed system, such as natural rock faults. The latter also display self-affine morphology with a persistent Hurst exponent. We will also address the main differences between a two-body and a three-body configuration in terms of wear volume and frictional work evolution.
Practical information
- General public
- Free
Organizer
- MEGA.Seminar Organizing Committee