Green’s function molecular dynamics meets discrete dislocation plasticity

The contact between rough metallic bodies almost always involves plastic flow in the area of real contact. We performed indentation experiments on sandblasted aluminum surfaces to explore the plastic deformation of asperities and modeled the contact mechanics using the boundary element method, combined with a simple numerical procedure to take into account the plastic flow. The theory can quantitatively describe the modification of the roughness by the plastic flow. Since the long-wavelength roughness determines the fluid leakage of metallic seals in most cases, we predict that the leakage can be estimated based on the elastoplastic contact mechanics model employed here.

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“…This BEM-based elastoplastic approach has also been frequently employed in other works, see e.g. [18,20,[43][44][45][46][47][48].…”

Section: Numerical Simulationmentioning

confidence: 99%

Plastic Deformation of Rough Metallic Surfaces

2020

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“…The boundary value solution is obtained at each time interval and at each material point as a whole of dislocation fields and their image fields [15]. The image fields can then be calculated by using finite elements or by using Green's function molecular dynamics (GFMD) [69].…”

Section: Discrete Dislocation Dynamics (Ddd)mentioning

confidence: 99%

Practice of Simulation and Life Cycle Assessment in Tribology—A Review

Kurdi

Alhazmi

et al. 2020

Materials

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To simulate today’s complex tribo-contact scenarios, a methodological breakdown of a complex design problem into simpler sub-problems is essential to achieve acceptable simulation outcomes. This also helps to manage iterative, hierarchical systems within given computational power. In this paper, the authors reviewed recent trends of simulation practices in tribology to model tribo-contact scenario and life cycle assessment (LCA) with the help of simulation. With the advancement of modern computers and computing power, increasing effort has been given towards simulation, which not only saves time and resources but also provides meaningful results. Having said that, like every other technique, simulation has some inherent limitations which need to be considered during practice. Keeping this in mind, the pros and cons of both physical experiments and simulation approaches are reviewed together with their interdependency and how one approach can benefit the other. Various simulation techniques are outlined with a focus on machine learning which will dominate simulation approaches in the future. In addition, simulation of tribo-contacts across different length scales and lubrication conditions is discussed in detail. An extension of the simulation approach, together with experimental data, can lead towards LCA of components which will provide us with a better understanding of the efficient usage of limited resources and conservation of both energy and resources.

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“…GFMD is a method allowing a linearly elastic boundaryvalue problem to be solved efficiently (Campañá and Müser, 2006;Venugopalan et al, 2017;Zhou et al, 2019). The (discretized) surface displacement field reflects the dynamical degrees of freedom.…”

Section: Thermal Gfmdmentioning

confidence: 99%

How Thermal Fluctuations Affect Hard-Wall Repulsion and Thereby Hertzian Contact Mechanics

2019

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Contact problems as they occur in tribology and colloid science are often solved with the assumption of hard-wall and hard-disk repulsion between locally smooth surfaces. This approximation is certainly meaningful at sufficiently coarse scales. However, at small scales, thermal fluctuations can become relevant. In this study, we address the question how they render non-overlap constraints into finite-range repulsion. To this end, we derive a closed-form analytical expression for the potential of mean force between a hard wall and a thermally fluctuating, linearly elastic counterface. Theoretical results are validated with numerical simulations based on the Green's function molecular dynamics technique, which is generalized to include thermal noise while allowing for hard-wall interactions. Applications consist of the validation of our method for flat surfaces and the generalization of the Hertzian contact to finite temperature. In both cases, similar force-distance relationships are produced with effective potentials as with fully thermostatted simulations. Analytical expressions are identified that allow the thermal corrections to the Hertzian load-displacement relation to be accurately estimated. While these corrections are not necessarily small, they turn out surprisingly insensitive to the applied load.

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Green’s function molecular dynamics meets discrete dislocation plasticity

Cited by 19 publications

References 48 publications

Plastic Deformation of Rough Metallic Surfaces

Plastic Deformation of Rough Metallic Surfaces

Practice of Simulation and Life Cycle Assessment in Tribology—A Review

How Thermal Fluctuations Affect Hard-Wall Repulsion and Thereby Hertzian Contact Mechanics

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