scholarly journals Molecular Dynamics Simulation on Thin-Film Lubrication of a Mixture of Three Alkanes

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3689
Author(s):  
Run Du ◽  
Anying Zhang ◽  
Zhihua Du ◽  
Xiaoyu Zhang
Keyword(s):  
Thin Film ◽  
Molecular Dynamics ◽  
Film Thickness ◽  
Md Simulation ◽  
Dynamics Simulation ◽  
Thin Film Lubrication ◽  
Thickness Change ◽  
Density Peaks ◽  
Initial Film ◽  
Film Lubrication

We used the COMPASS forcefield to perform molecular dynamics (MD) simulation of a mixture composed of three alkanes as the lubricant for the thin-film lubrication. The viscosity of the lubrication film in the non-working state, the final film thickness, and density distribution were investigated. The results reveal that the viscosity error among different initial film thicknesses in the non-working state is within 5%, which confirms the applicability of the model and the forcefield. The viscosity decreases oscillating as temperature increases. Whatever the initial film thickness is, the film thickness change rate with respect to pressure load is almost the same. When pressure increases, the density peaks increase. As the initial film thickness increases, the normalized thicknesses of adsorption and ordered layers decrease. In nanoscale, the density predicted by the MD simulation is higher than the prediction of the Tait equation, even if the adsorption layers is excluded.

A New Postulation of Viscosity and Its Application in Computation of Film Thickness in TFL1

2002 ◽  
Vol 124 (4) ◽  
pp. 811-814 ◽  
Author(s):  
Chaohui Zhang ◽  
Jianbin Luo ◽  
Shizhu Wen
Keyword(s):  
Thin Film ◽  
Experimental Data ◽  
Film Thickness ◽  
Solid Surface ◽  
Contact Area ◽  
Elastohydrodynamic Lubrication ◽  
Thin Film Lubrication ◽  
Lubrication Film ◽  
Viscosity Modification ◽  
Film Lubrication

In this paper, a viscosity modification model is developed which can be applied to describe the thin film lubrication problems. The viscosity distribution along the direction normal to solid surface is approached by a function proposed in this paper. Based on the formula, lubricating problem of thin film lubrication (TFL) in isothermal and incompressible condition is solved and the outcome is compared to the experimental data. In thin film lubrication, according to the computation outcomes, the lubrication film thickness is much greater than that in elastohydrodynamic lubrication (EHL). When the velocity is adequately low (i.e., film thickness is thin enough), the pressure distribution in the contact area is close to Hertzian distribution in which the second ridge of pressure is not obvious enough. The film shape demonstrates the earlobe-like form in thin film lubrication, which is similar to EHL while the film is comparatively thicker. The transformation relationships between film thickness and loads, velocities or atmosphere viscosity in thin film lubrication differ from those in EHL so that the transition from thin film lubrication to EHL can be clearly seen.

Molecular Dynamics Simulation on the Out-of Plane Thermal Conductivity of Single-Crystal Carbon Thin Films

2009 ◽  
Vol 60-61 ◽  
pp. 430-434 ◽  
Author(s):  
Xing Li Zhang ◽  
Zhao Wei Sun ◽  
Guo Qiang Wu
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Potential Energy ◽  
Film Thickness ◽  
Single Crystal ◽  
Diamond Crystal ◽  
Dynamics Simulation ◽  
Crystal Direction

In this article, we select corresponding Tersoff potential energy to build potential energy model and investigate the thermal conductivities of single-crystal carbon thin-film. The equilibrium molecular dynamics (EMD) method is used to calculate the nanometer thin film thermal conductivity of diamond crystal at crystal direction (001), and the non-equilibrium molecular dynamics (NEMD) is used to calculate the nanometer thin film thermal conductivity of diamond crystal at crystal direction (111). The results of calculations demonstrate that the nanometer thin film thermal conductivity of diamond crystal is remarkably lower than the corresponding bulk experimental data and increase with increasing the film thickness, and the nanometer thin film thermal conductivity of diamond crystal relates to film thickness linearly in the simulative range. The nanometer thin film thermal conductivity also demonstrates certain regularity with the change of temperature. This work shows that molecular dynamics, applied under the correct conditions, is a viable tool for calculating the thermal conductivity of nanometer thin films.

Molecular dynamics simulation of surface morphology during homoepitaxial growth of Copper

2019 ◽  
Vol 87 (3) ◽  
pp. 31301 ◽  
Author(s):  
Hicham El Azrak ◽  
Abdessamad Hassani ◽  
Abdelhadi Makan ◽  
Fouad Eddiai ◽  
Khalid Sbiaai ◽  
...  
Keyword(s):  
Thin Film ◽  
Molecular Dynamics ◽  
Surface Roughness ◽  
Surface Morphology ◽  
Md Simulation ◽  
Dynamics Simulation ◽  
Embedded Atom Method ◽  
Homoepitaxial Growth ◽  
Embedded Atom ◽  
Rough Surface Morphology

In this paper, molecular dynamics (MD) simulation of surface morphology during homoepitaxial growth of Copper was investigated. For this purpose, simulations of Cu deposition on the Cu(111) substrate with an incidence energy of 0.06 eV at 300K were performed using the embedded-atom method (EAM). The grown thin film on Cu(111) reveled a rough surface morphology. During deposition, the important fraction of atoms intended for the upper layers undergone a rising rate of about 40% starting from the 2nd period and continued to increase until 65%, while the lower level reached a permanent rate of only 25% by the 4th period. Otherwise, except at the first layer level, the lower layers are incomplete. This void in the lower layers has favored the growth of the upper layers until a rate of 143% and has accelerated their time appearance. Th incidence energy has favored the filling of lower layers by reducing this surface roughness. However, the temperature effect needs more relaxation time to fill the lower layers.

Atomistic Simulations of Dislocation-Loop Glidings in Al(111) Nanoindentation

2004 ◽  
Vol 261-263 ◽  
pp. 735-740
Author(s):  
Sukky Jun ◽  
Young Min Lee ◽  
Sung Youb Kim ◽  
Se Young Im
Keyword(s):  
Thin Film ◽  
Molecular Dynamics ◽  
Film Thickness ◽  
Dislocation Loop ◽  
Dislocation Motion ◽  
Dynamics Simulation ◽  
Atomistic Simulations ◽  
Dislocation Loops ◽  
Simulation Results ◽  
Film Nucleation

Molecular dynamics simulation of nanoindentation on Al(111) surface is presented. The simulation is performed using the Ercolessi-Adams glue potential and the Berendsen thermostat. Boundary conditions of 'pseudo' thin film are imposed in order to focus on the dislocation motion in ultra-thin film. Nucleation and development of defects underneath the indenter tip are visualized, and the gliding patterns of dislocation loops are investigated with particular emphasis on the effect of film thickness. Simulation results show that the early emission of dislocation loop is highly dependent on the film thickness.

Integration of a Molecular Viscosity Model and a Continuum EHL Solution for Simulation of Thin Film Lubrication

2005 ◽  
Author(s):  
A. Martini ◽  
Y. Liu ◽  
R. Q. Snurr ◽  
Q. Wang
Keyword(s):  
Thin Film ◽  
Film Thickness ◽  
Molecular Model ◽  
Viscosity Model ◽  
Simulation Approach ◽  
Thin Film Lubrication ◽  
Molecular Film ◽  
Lubricated Contact ◽  
Molecular Viscosity ◽  
Film Lubrication

We present a simulation approach for thin film lubrication that integrates a molecular model of the film thickness-viscosity relationship in thin films with a continuum elastohydrodynamic (EHL) lubricated contact solution. Molecular simulation is used to characterize the effect of film thickness on viscosity in terms of solidification, shear thinning, and oscillation. This relationship is then incorporated into a traditional, continuum EHL solution. Film thickness distributions predicted by this integrated model are evaluated. It is found that the effect of the molecular film thickness-viscosity model is small compared to the increase in viscosity with pressure predicted by the Barus equation.

scholarly journals Molecular Dynamics Simulation on B3-GaN Thin Films under Nanoindentation

Nanomaterials ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 856 ◽  
Author(s):  
Chen Chen ◽  
Haitao Li ◽  
Henggao Xiang ◽  
Xianghe Peng
Keyword(s):  
Thin Film ◽  
Molecular Dynamics ◽  
Large Scale ◽  
Md Simulation ◽  
Orientation Dependence ◽  
Dynamics Simulation ◽  
Formation Mechanisms ◽  
Plastic Behavior ◽  
Prismatic Dislocation Loop ◽  
Prismatic Loop

The B3-GaN thin film was investigated by performing large-scale molecular dynamics (MD) simulation of nanoindentation. Its plastic behavior and the corresponding mechanism were studied. Based on the analysis on indentation curve, dislocation density, and orientation dependence, it was found that the indentation depths of inceptive plasticity on (001), (110), and (111) planes were consistent with the Schmid law. The microstructure evolutions during the nanoindentation under different conditions were focused, and two formation mechanisms of prismatic loop were proposed. The “lasso”-like mechanism was similar to that in the previous research, where a shear loop can translate into a prismatic loop by cross-slip; and the extended “lasso”-like mechanism was not found to be reported. Our simulation showed that the two screw components of a shear loop will glide on another loop until they encounter each other and eventually produce a prismatic dislocation loop.

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