Nanoparticle Friction Force and Effective Viscosity of Nanosuspensions

2008 ◽  
Vol 273-276 ◽  
pp. 566-571 ◽  
Author(s):  
Valery Rudyak ◽  
A.A. Belkin ◽  
E.A. Tomilina ◽  
V.V. Egorov
Keyword(s):  
Molecular Dynamics ◽  
Friction Coefficient ◽  
Friction Force ◽  
Effective Viscosity ◽  
Volume Concentration ◽  
Massive Particle ◽  
Viscosity Coefficient ◽  
Initial Stage ◽  
Stokes Force ◽  
Dynamics Method

The transport properties of nanofluids are investigated by the molecular dynamics method. It is shown that the force acting on a nanoparticle is nonstationary, in contrast to the Stokes force. In the initial stage of relaxation, the friction force is greater than the Stokes value. Subsequently, this force decreases and reaches an asymptotic value. This value is comparable to the Stokes force only for a massive particle. A correlation for determining the friction coefficient is constructed. It is established that the effective viscosity coefficient of nanofluids depends not only on the volume concentration of nanoparticles but also on the nanoparticle mass and radius.

scholarly journals Study of Nanoscratching Process of GaAs Using Molecular Dynamics

Crystals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 321 ◽  
Author(s):  
Defu Yi ◽  
Jianyong Li ◽  
Pengzhe Zhu
Keyword(s):  
Molecular Dynamics ◽  
Phase Transformation ◽  
Hydrostatic Pressure ◽  
Friction Coefficient ◽  
Chemical Mechanical Polishing ◽  
Mechanical Polishing ◽  
Deformation Mechanisms ◽  
Deformation Behaviors ◽  
Dynamics Method ◽  
Shed Light

In this paper, molecular dynamics method was employed to investigate the nanoscratching process of gallium arsenide (GaAs) in order to gain insights into the material deformation and removal mechanisms in chemical mechanical polishing of GaAs. By analyzing the distribution of hydrostatic pressure and coordination number of GaAs atoms, it was found that phase transformation and amorphization were the dominant deformation mechanisms of GaAs in the scratching process. Furthermore, anisotropic effect in nanoscratching of GaAs was observed. The diverse deformation behaviors of GaAs with different crystal orientations were due to differences in the atomic structure of GaAs. The scratching resistance of GaAs(001) surface was the biggest, while the friction coefficient of GaAs(111) surface was the smallest. These findings shed light on the mechanical wear mechanism in chemical mechanical polishing of GaAs.

Study on Interactive Multi-resolution Molecular Dynamics Method

2000 ◽  
Vol 20 (1Supplement) ◽  
pp. 43-46
Author(s):  
Ken-ichi SAITOH ◽  
Takashi DOI ◽  
Masao KOMAYA ◽  
Takehiko INABA
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Method ◽  
Dynamics Method

Effect of shape/size and distribution of microgeometries of textures on tribo-performance of crankpin bearing

2021 ◽  
pp. 135065012110105
Author(s):  
Nguyen Van Liem ◽  
Wu Zhenpeng ◽  
Jiao Renqiang
Keyword(s):  
Friction Coefficient ◽  
Friction Force ◽  
Contact Force ◽  
Distribution Density ◽  
Hydrodynamic Lubrication ◽  
Operating Conditions ◽  
Asperity Contact ◽  
Combined Model ◽  
Obvious Effect ◽  
Area Density

The effect of the shape/size and distribution of microgeometries of textures on improving the tribo-performance of crankpin bearing is proposed. Based on a combined model of the slider-crank mechanism dynamic and hydrodynamic lubrication, the distribution density, area density, and shape of spherical textures, square-cylindrical textures, wedge-shaped textures, and a hybrid between spherical texture and square-cylindrical texture on the crankpin bearing's tribo-performance are investigated under different operating conditions of the engine. The tribological characteristic of the crankpin bearing is then evaluated via the indexes of the oil film pressure p, asperity contact force, friction force, and friction coefficient of the crankpin bearing. The research results show that the distribution density with n = 12 and m = 6, and area density with α = 30% of various microtextures have an obvious effect on ameliorating the crankpin bearings tribo-performance. Concurrently, at the mixed lubrication region, the shape of the square-cylindrical texture on improving the tribo-performance is better than the other shapes of the spherical texture, wedge-shaped texture, and spherical and square-cylindrical texture. Particularly, all the average values of the asperity contact force, friction force, and friction coefficient with a square-cylindrical texture are significantly reduced by 14.6%, 19.5%, and 34.5%, respectively, in comparison without microtextures. Therefore, the microtextures of the spherical texture applied on the bearing surface can contribute to enhance the durability and decrease the friction power loss of the engine.

scholarly journals Influence of Nanoscale Textured Surfaces and Subsurface Defects on Friction Behaviors by Molecular Dynamics Simulation

Nanomaterials ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1617 ◽  
Author(s):  
Ruiting Tong ◽  
Zefen Quan ◽  
Yangdong Zhao ◽  
Bin Han ◽  
Geng Liu
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Friction Force ◽  
Copper Substrate ◽  
Dynamics Simulation ◽  
Textured Surfaces ◽  
Friction Forces ◽  
Subsurface Structures ◽  
Texture Orientation ◽  
Subsurface Defects

In nanomaterials, the surface or the subsurface structures influence the friction behaviors greatly. In this work, nanoscale friction behaviors between a rigid cylinder tip and a single crystal copper substrate are studied by molecular dynamics simulation. Nanoscale textured surfaces are modeled on the surface of the substrate to represent the surface structures, and the spacings between textures are seen as defects on the surface. Nano-defects are prepared at the subsurface of the substrate. The effects of depth, orientation, width and shape of textured surfaces on the average friction forces are investigated, and the influence of subsurface defects in the substrate is also studied. Compared with the smooth surface, textured surfaces can improve friction behaviors effectively. The textured surfaces with a greater depth or smaller width lead to lower friction forces. The surface with 45° texture orientation produces the lowest average friction force among all the orientations. The influence of the shape is slight, and the v-shape shows a lower average friction force. Besides, the subsurface defects in the substrate make the sliding process unstable and the influence of subsurface defects on friction forces is sensitive to their positions.

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