Molecular Dynamics Simulation Study of Tool Wear in Vibration Assisted Nano-Impact-Machining by Loose Abrasives

2014 ◽  
Vol 3 (1) ◽  
Author(s):  
Sagil James ◽  
Murali M. Sundaram
Keyword(s):  
Molecular Dynamics ◽  
Tool Wear ◽  
Machining Process ◽  
Dynamics Simulation ◽  
Process Conditions ◽  
Wear Process ◽  
Tool Wear Mechanism ◽  
Novel Target ◽  
Tip Radius ◽  
The Impact

Vibration assisted nano-impact-machining by loose abrasives (VANILA) is a novel target specific nano-abrasive machining process wherein, nano-abrasives, injected in slurry between the workpiece and the vibrating atomic force microscope probe, impact the workpiece causing nanoscale material removal. In this study, a molecular dynamics (MD) based simulation approach is used to investigate the tool wear mechanism. The simulation results reveal that the tool wear is influenced by the impact velocity of the abrasive grains and the effective tool tip radius. It is seen that based on the process conditions, the wear process could happen through distinctive mechanisms such as atom-by-atom loss, plastic deformation, and brittle fracture. Experimental results show evidences of tool wear by aforementioned mechanisms in VANILA process.

Investigation on Performance of a CVD Coated Carbide Tool in Face Milling of Ultra-High Strength Steel 30Cr3SiNiMoVA

2014 ◽  
Vol 800-801 ◽  
pp. 440-445
Author(s):  
Jin Bang Song ◽  
Chang Ying Wang ◽  
Lin Zan ◽  
Ming Chen
Keyword(s):  
Tool Wear ◽  
High Strength Steel ◽  
High Strength ◽  
Face Milling ◽  
Machining Process ◽  
Wear Process ◽  
Coated Tools ◽  
Ultra High Strength Steel ◽  
Tool Wear Mechanism ◽  
Coated Carbide

Ultra-high strength steel 30Cr3SiNiMoVA is a typical difficult-to-cut material. During the machining process of 30Cr3SiNiMoVA, tool wear is an important factor which needs to be investigated seriously. In this work, one kind of CVD coated tools was used to investigate the tool wear mechanism of face milling of Ultra-high Strength Steel 30Cr3SiNiMoVA. Cutting forces during the wear process were measured with a kistler dyna-mometer. Surface roughness and tool wear evolution were determined.

scholarly journals The Impact of the Electric Field on Surface Condensation of Water Vapor: Insight from Molecular Dynamics Simulation

Nanomaterials ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 64 ◽  
Author(s):  
Qin Wang ◽  
Hui Xie ◽  
Zhiming Hu ◽  
Chao Liu
Keyword(s):  
Molecular Dynamics ◽  
Water Vapor ◽  
Electric Field ◽  
Intermolecular Forces ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Attraction Force ◽  
Condensation Rate ◽  
Shape Transformation ◽  
The Impact

In this study, molecular dynamics simulations were carried out to study the coupling effect of electric field strength and surface wettability on the condensation process of water vapor. Our results show that an electric field can rotate water molecules upward and restrict condensation. Formed clusters are stretched to become columns above the threshold strength of the field, causing the condensation rate to drop quickly. The enhancement of surface attraction force boosts the rearrangement of water molecules adjacent to the surface and exaggerates the threshold value for shape transformation. In addition, the contact area between clusters and the surface increases with increasing amounts of surface attraction force, which raises the condensation efficiency. Thus, the condensation rate of water vapor on a surface under an electric field is determined by competition between intermolecular forces from the electric field and the surface.

Molecular Dynamics Studies on the Growth and Structural Properties of Hydrogenated DLC Films

2008 ◽  
Vol 373-374 ◽  
pp. 108-112
Author(s):  
Yu Jun Zhang ◽  
Guang Neng Dong ◽  
Jun Hong Mao ◽  
You Bai Xie
Keyword(s):  
Molecular Dynamics ◽  
Structural Properties ◽  
Impact Energy ◽  
Frictional Coefficient ◽  
Carbon Films ◽  
Dynamics Simulation ◽  
Diamond Surface ◽  
Hydrogen Atoms ◽  
Molecular Configuration ◽  
The Impact

The novel frictional properties of hydrogenated DLC (Diamond-like Carbon) films have been reported for nearly ten years. But up to now, researchers still haven’t known the exact mechanism resulting in the super-low frictional performance of hydrogenated DLC films. Especially they have little knowledge on the molecular configuration and structural properties of these kinds of films. In this paper, CH3 radicals with different impact energies are selected as source species to deposit DLC films on diamond (100) by molecular dynamics simulation. Results show hydrogenated DLC films can be successfully obtained when impact energy is in an appropriate scope that is no less than 20eV. The depositing processes involve impinging diamond surface and bonding procedure. Some atoms, instead of bonding with substrate atoms, fly away from the diamond surface. Only suitable impact energy can improve the growth of the film. Within 30eV to 60eV, the maximum deposition ratio is attained. In addition, when carbon atoms act as the deposition sources, the deposition ratio is relatively higher. Furthermore, the authors find that species with higher concentration of carbon atoms in deposition sources lead to a better deposition rate. Carbon atoms are more reactive than hydrogen atoms. Then the relative densities of DLC films are calculated. The density curves indicate that the structures of the films vary obviously as the impact energy augments. The average relative density is generally monotone increase with the increment of impact energy. The hybridization of carbon atoms greatly affects the properties of hydrogenated DLC films. The transition between sp2 and sp3 will result in the graphitization and reduce the frictional coefficient when DLC films are used as tribo-pair in friction.

scholarly journals Material Analysis and Molecular Dynamics Simulation for Cavitation Erosion and Corrosion Suppression in Water Hydraulic Valves

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 453 ◽  
Author(s):  
Masoud Kamoleka Mlela ◽  
He Xu ◽  
Feng Sun ◽  
Haihang Wang ◽  
Gabriel Donald Madenge
Keyword(s):  
Molecular Dynamics ◽  
Md Simulation ◽  
Essential Role ◽  
Corrosion Inhibitors ◽  
Cavitation Erosion ◽  
Dynamics Simulation ◽  
Preference Ranking ◽  
Water Hydraulics ◽  
The Impact ◽  
Hydraulic Valves

In the milestone of straggling to make water hydraulics more advantageous, the choice of coating polymer for water hydraulics valves plays an essential role in alleviating the impact of cavitation erosion and corrosion, and this is a critical task for designers. Fulfilling the appropriate selection, we conflicted properties that are vital for erosion and corrosion inhibitors, as well as the tribology in the sense of coefficient of friction. This article aimed to choose the best alternative polymer for coating on the selected substrate, that is, Cr2O3, Al2O3, Ti2O3. By applying PROMETHEE (Preference Ranking Organization Method for Enrichment Evaluations), the best polymer obtained with an analyzed performance attribute is Polytetrafluoroethylene (PTFE) that comes up with higher outranking (0.5932052). A Molecular Dynamics (MD) simulation was conducted to identify the stronger bonding with the regards of the better cleave plane between Polytetrafluoroethylene (PTFE) and the selected substrate. Polytetrafluoroethylene (PTFE)/Al2O3 cleaved in (010) plane was observed to be the strongest bond in terms of binding energy (3188 kJ/mol) suitable for further studies.

Molecular Dynamics Simulations of Structures of Amorphous Carbon Films via Deposition

2011 ◽  
Vol 194-196 ◽  
pp. 2220-2224
Author(s):  
Hui Qing Lan ◽  
Zheng Ling Kang
Keyword(s):  
Molecular Dynamics ◽  
Amorphous Carbon ◽  
Growth Dynamics ◽  
Carbon Films ◽  
Film Structure ◽  
Dynamics Simulation ◽  
Carbon Ions ◽  
Amorphous Carbon Films ◽  
Dynamics Simulations ◽  
The Impact

The growth of amorphous carbon films via deposition is investigated using molecular dynamics simulation with a modified Tersoff potential. The impact energy of carbon atoms ranges from 1 to 50 eV and the temperature of the diamond substrate is 300 K. The effects of the incident energy on the growth dynamics and film structure are studied in a detail. Simulation results show that the mobility of surface atoms in the cascade region is enhanced by impacting energetic carbon ions, especially at moderate energy, which favors the growth of denser and smoother films with better adhesion to the substrate. Our results agree qualitatively with the experimental observation.

scholarly journals Preparation and Molecular Dynamics Simulation of RDX/MUF Nanocomposite Energetic Microspheres with Reduced Sensitivity

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 692
Author(s):  
Jia ◽  
Hu ◽  
Xu ◽  
Liu ◽  
Ma ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Binding Energy ◽  
Emulsion Polymerization ◽  
Md Simulation ◽  
Urea Formaldehyde ◽  
Urea Formaldehyde Resin ◽  
Experimental Results ◽  
Dynamics Simulation ◽  
Formaldehyde Resin ◽  
Process Conditions

In order to improve the general problem of irregular coating morphology and low mechanical strength of the coating layer in existing coating desensitization technology, nano-cyclotrimethylene trinitramine/melamine-urea-formaldehyde (RDX/MUF) composite energetic microspheres were prepared by an improved emulsion polymerization, taking the MUF as the binder and RDX as the main explosive. In order to judge whether RDX/MUF possessed good stability, the combination of differential scanning calorimetry (DSC) and molecular dynamics (MD) simulation was used to determine the level of binding binding energy between urea-formaldehyde resin binder (UF) and RDX. In addition, to investigate the optimal reaction temperature for the preparation of MUF/RDX, the binding energy between UF and RDX at different temperatures was simulated. And then the morphology and thermal properties of the as-prepared composite energetic microspheres were analyzed by scanning electron microscopy (SEM) and DSC, the impact sensitivity and friction sensitivity of the resultant samples were tested as well. Moreover, RDX/MUF with the same MUF content was prepared by physical mixing for comparative analysis. MD simulation demonstrated that UF and RDX possessed good binding ability at 298 K. The DSC method indicatec that UF and RDX had good compatibility, and the comprehensive performance of RDX after coating was not significantly deteriorated; The optimal binding temperature between UF and RDX was 60~70 °C which is consistent with the experimental results. The experimental results showed that the optimum process conditions for the preparation of RDX/MUF could be listed as follows: the temperature for preparing RDX/MUF composite energetic microspheres by the improved emulsion polymerization was 70 °C the optimal pH value of the urea-formaldehyde resin prepolymer solution was 3, and the optimal melamine-urea molar ratio was 0.4.

Comparison of the effect of poly(N-vinyl caprolactam) and poly(N-isopropyl acrylamide) trimers on the stability of hydrated Na-montmorillonite: A molecular dynamics study

2020 ◽  
pp. 096739112093524
Author(s):  
Jiafang Xu ◽  
Moussa Camara ◽  
Hualin Liao ◽  
Hong Guo ◽  
Kouassi Louis Kra ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Conformational Changes ◽  
Stable State ◽  
Dynamics Simulation ◽  
Effect Of Temperature ◽  
Radius Of Gyration ◽  
Molecular Arrangement ◽  
Isopropyl Acrylamide ◽  
The Stability ◽  
The Impact

In the present study, we performed a molecular dynamics simulation of the intercalation of poly( N-isopropyl acrylamide) (NIPAM)3 and poly( N-vinyl caprolactam) (NVCL)3 trimers into Na-montmorillonite (Na-Mt) to evaluate their effects on the interlayer structure and the stability of hydrated Na-Mt. The impact of both trimers on the interlayer species and their dynamics properties at different temperatures in a canonical ensemble (NVT) were investigated. The results showed that the electrostatic forces exerted by Na cations on H2O molecules and the interlayer H2O molecular arrangement are not affected by the rise in temperature after adding both trimers. Trimer addition reinforced the structure of interlayer H2O molecules so that the effect of temperature increase on them became negligible. The structural dynamics evolution of the radius of gyration of both trimers showed the existence of conformation changes when temperature increased. These conformational changes are more complex in the case of (NVCL)3 than (NIPAM)3 due to its large monomers. Both trimers reduced the mobility of interlayer particles with a better inhibition effect obtained for (NVCL)3 compared to (NIPAM)3. The concentration profile of interlayers’ species showed the affinity of Na cations for clay mineral surfaces while H2O molecules moved away. Compared these two trimers, the most stable state of Na-Mt is achieved with (NVCL)3. These results could help highlight the inhibition properties of (NIPAM)3 and (NVCL)3 on hydrated Na-Mt and to predict its stability against changes in environmental conditions.

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