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.

Multiscale Analysis on Friction-Reducing Characteristics of Textured Surface in Nanoscale Sliding Contacts

2011 ◽  
Vol 86 ◽  
pp. 649-652
Author(s):  
Rui Ting Tong ◽  
Geng Liu ◽  
Lan Liu ◽  
Shang Jun Ma
Keyword(s):  
Copper Substrate ◽  
Dynamics Simulation ◽  
Textured Surface ◽  
Face Centered Cubic ◽  
Textured Surfaces ◽  
Sliding Contacts ◽  
Friction Forces ◽  
Surface Textures ◽  
Force Reduction ◽  
Face Centered

A multiscale method coupled molecular dynamics simulation and finite element method is used to investigate two dimensional nanoscale sliding contacts between a rigid cylindrical tip and an elastic face centered cubic copper substrate with textured surface, in which adhesive effects are considered. Two series of nanoscale surface textures with different asperity shape, different asperity heights and different spacing between asperities are designed. Through the friction forces comparisons between smooth surface and textured surfaces, a better shape is advised to indicate that asperity shape plays an important role in friction force reduction. With proper asperity height and proper spacing between asperities, surface textures can reduce friction forces effectively.

Molecular dynamics simulation of grain size effect on friction and wear of nanocrystalline zirconium

2020 ◽  
pp. 135065012094507
Author(s):  
Kehao Zhu ◽  
Xiaoyu Zhang ◽  
Xinlu Yuan ◽  
Gen Li ◽  
Pingdi Ren
Keyword(s):  
Molecular Dynamics ◽  
Grain Size ◽  
Molecular Dynamics Simulation ◽  
Friction And Wear ◽  
Atomic Displacement ◽  
Dynamics Simulation ◽  
Friction Forces ◽  
Grain Sizes ◽  
Crystalline Substrate ◽  
Boundary Rotation

In this study, molecular dynamics simulation was conducted to investigate the frictional behaviors between diamond tool and zirconium (Zr) substrates at the nanoscale. The effects of grain size on friction and wear were discussed under different sliding velocities. The simulation results showed that the friction forces had similar variation tendencies under different sliding velocities. Besides, the friction responses were stronger at high sliding velocities because of the atomic adhesion while the ploughing effect was more obvious at slower sliding velocity. Moreover, both the friction forces and the wear amounts increased with the decrease in the average grain sizes of the substrates. To explain this phenomenon, the internal mechanism was investigated by using the dislocation extract algorithm and the atomic displacement analyses. The results showed that the [0001]-oriented single crystalline substrate was prone to form continuous dislocation structures moving tangentially along the sliding direction due to the characteristic of Zr's slip systems, whereas grain boundaries conducted the deformation further into the polycrystalline substrates, increasing the contact areas and causing atomic accumulation in front, both resulted in stronger friction responses and wear. Accordingly, with the decrease in average grain sizes, the substrates experienced more severe subsurface damage and the deformation mechanism of nanocrystalline Zr had evolved from dislocation emission to grain boundary rotation and sliding.

AFM-Based Nanoscratching: A 3D Molecular Dynamics Simulation With Experimental Verification

2014 ◽  
Author(s):  
Rapeepan Promyoo ◽  
Hazim El-Mounayri ◽  
Kody Varahramyan
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Md Simulation ◽  
Three Dimensional ◽  
Dynamics Simulation ◽  
Dimensional Model ◽  
Gold Substrate ◽  
Three Dimensional Model ◽  
Friction Forces ◽  
Defect Mechanism

In this paper, a developed three-dimensional model for AFM-based nanomachining is applied to study mechanical scratching at the nanoscale. The correlation between the scratching conditions, including applied force, scratching depth, and distant between any two scratched grooves, and the defect mechanism in the substrate/workpiece is investigated. The simulations of nanoscratching process are performed on different crystal orientations of single-crystal gold substrate, Au(100), Au(110), and Au(111). The material deformation and groove geometry are extracted from the final locations of atoms, which are displaced by the rigid indenter. The simulation also allows for the prediction of normal and friction forces at the interface between the indenter and substrate. An AFM is used to conduct actual scratching at the nanoscale, and provide measurements to which the MD simulation predictions are compared. The predicted forces obtained from MD simulation compares qualitatively with the experimental results.

Molecular Dynamics Simulation of Vibrational Friction Force Due to Molecular Deformation in Confined Lubricant Film

2003 ◽  
Vol 125 (3) ◽  
pp. 587-591 ◽  
Author(s):  
Kentaro Tanaka ◽  
Takahisa Kato ◽  
Yoichiro Matsumoto
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Friction Force ◽  
Lubricant Film ◽  
Dynamics Simulation ◽  
Radius Of Gyration ◽  
Magnetic Storage ◽  
Stick Slip ◽  
Molecular Deformation ◽  
Load Conditions

The lubrication by thin film has become a very important role in micro machine, magnetic storage device and so on. As the thickness of lubricant film becomes thinner to several nanometers, the conventional law of lubrication becomes unable to use. Nonequilibrium molecular dynamics simulation (NEMD) was carried out to investigate the dynamic behavior of thin lubricant film confined between walls. The model used in these simulations is composed of two solid walls and fluorocarbon polymer lubricant. One of the walls is supporting a load and at the same time moving at constant velocity. Results indicate that the frictional behavior of confined lubricant varied with load; velocity field in the film retain liquid like structure under low load conditions, on the other hand, under high load conditions lubricant film becomes solidified and periodical stick and slip motion is observed at the layer near the wall. At the same time periodically vibrating friction force is observed. In this case, radius of gyration of lubricant molecules also changes periodically. It is concluded that the periodical vibration of friction force is caused by stick-slip with molecular deformation.

Effect of Defects on Oscillatory Behaviors of Double-Walled Carbon Nanotube Oscillators

2011 ◽  
Vol 308-310 ◽  
pp. 584-588
Author(s):  
Jian Li
Keyword(s):  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Molecular Dynamics Simulation ◽  
Friction Force ◽  
Vacancy Defect ◽  
Defect Size ◽  
Dynamics Simulation ◽  
Vacancy Defects ◽  
The Core ◽  
Temperature Dependences

Molecular dynamics simulation is performed on the inter-tube friction force and energy dissipation of double-walled carbon nanotube oscillators with vacancy defects. It is found that there are vacancy defect-size and temperature dependences of the friction force between the inner tube and the defective outer tube. The original distance between the “hole” formed by the vacancy carbon atoms and the inserted end of the core has a significant influence on the oscillation profile.

Molecular Dynamics Simulation of the Thermal Resistance of Carbon Nanotube – Substrate Interfaces

2009 ◽  
Author(s):  
Daniel J. Rogers ◽  
Jianmin Qu ◽  
Matthew Yao
Keyword(s):  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Molecular Dynamics Simulation ◽  
Thermal Resistance ◽  
Copper Substrate ◽  
Harmonic Approximation ◽  
Thermal Conductance ◽  
Dynamics Simulation ◽  
Interfacial Thermal Resistance ◽  
Non Equilibrium Molecular Dynamics

The interfacial thermal resistance (ITR) between a carbon nanotube (CNT) and adjoining carbon, silicon, or copper substrate is investigated through non-equilibrium molecular dynamics simulation (NEMD). The theoretical phonon transmission also is calculated using a simplified form of the diffuse mismatch model (DMM) with direct simulation of the phonon density of states (DOS) under quasi-harmonic approximation. The results of theory and simulation are reported as a function of temperature in order to estimate the importance of anharmonicity and inelastic scattering. At 300K, the thermal conductance of CNT-substrate interfaces is ∼1500 W/mm2K for diamond carbon, ∼500 W/mm2K for silicon, and ∼250 W/mm2K for copper.

Molecular Dynamics Simulation of Nanoscale Sliding Friction Process between Sphere and Plane

2012 ◽  
Vol 268-270 ◽  
pp. 1134-1142 ◽  
Author(s):  
Xiao Jing Yang ◽  
Sheng Peng Zhan ◽  
Yi Lin Chi
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Friction Force ◽  
Basal Body ◽  
Contact Surface ◽  
Sliding Friction ◽  
Dynamics Simulation ◽  
Sliding Speed ◽  
Contact Depth ◽  
Macro Scale

Contact surface of nanoscale sliding friction represent some new features that are different from the macro scale sliding friction, which need to seek new analysis methods. Molecular dynamics simulation is an effective method to describe microscopic phenomena. Therefore, Molecular dynamics method was used to study mechanical behavior of contact surface of nanoscale sliding friction. A molecular dynamics model of hemisphere sphere sliding on rectangular solid plane was built. State change of the micro contact area and friction force variation in the process of sliding friction were observed and analyzed after solution and simulation. The results show that, at the beginning position of the sliding, with different contact depth, contact action region of hemisphere and plane generated the atoms displacement, re-arranged and close-packed accumulation is also different. The deeper the contact depth is, the greater the atoms close-packed accumulation is, and the greater the contact deformation is. In the process of sliding friction, the contact surface of the basal body has produced lattice destruction, surface upheaval and silicon atoms close-packed accumulation, and then formed furrow scratches. At the same time the silicon atoms of the hemisphere generated atomic migration obviously and adhered on the basal body surface. The top of the hemisphere was torn and peeled, which resulted in wear. The deeper contact depth is, the more loss of the material of the hemisphere is, and wear become heavier. The curve of friction force and sliding displacement in different contact depths shows that the deeper contact depth is, the greater friction force is. The friction force increases quickly at the beginning of the sliding. Then the friction force remains steady relatively at stable sliding phase. In subsequent sliding process, due to hemisphere was worn and the original contact surface changed in size, shape and configuration state, friction force decreases obviously. Besides, in process of sliding friction, due to stick-slip effect, friction force appears obviously fluctuations. Moreover, if the sliding speed is large the changes of sliding speed have less effect on friction force when the nanoscale sphere sliding on the plane at the different speeds.

Molecular Dynamics Simulation of Confined n-Alkanes Between Nano-Asperity Walls

2012 ◽  
Author(s):  
Xuan Zheng ◽  
Hongtao Zhu ◽  
A. Kiet Tieu
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Chain Length ◽  
Friction Force ◽  
Normal Load ◽  
Dynamics Simulation ◽  
Metal Contact ◽  
Asperity Contact ◽  
Contact Interface ◽  
Local Lattice

A molecular dynamics simulation of confined n-alkanes is conducted to investigate the effect of chain length (C8, C16, C32, C64) and normal load (250, 500, 750, 1000MPa) on friction and asperity contact. The results indicate that the longer chain n-alkanes maintain more monolayer atoms in the asperity contact interface than the shorter ones and as a result significantly reduce the friction force. Under a normal load of 250MPa, the asperity with C32 and C64 are separated by the lubricant with less metal contact. Periodic friction force is observed and it correlates with the deformation of the local lattice that breaks and relocates the atoms during the asperity contact.

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