Study on the Effect of Different Factors of Displacement Cascades in Alpha-Fe by Molecular Dynamics Simulations

2020 ◽  
Author(s):  
Pandong Lin ◽  
Junfeng Nie ◽  
Meidan Liu
Keyword(s):  
Molecular Dynamics ◽  
Tensile Strain ◽  
Vacancy Concentration ◽  
Irradiation Damage ◽  
Effect Of Temperature ◽  
Displacement Cascade ◽  
Rpv Steel ◽  
Dynamics Simulations ◽  
Dynamics Method

Abstract As the key component of RPV steel, α-Fe is under neutron irradiation during its long-term service, and lattice atoms of α-Fe are knocked by neutrons, which leads to irradiation damage. In this paper, molecular dynamics method is conducted to investigate the effect of temperature, vacancy concentration and tensile strain on irradiation-induced damage by displacement cascade simulations in α-Fe. The simulations are performed with primary knock-on atom energies ranging from 0.1 to 5 keV, temperature ranging from 100 to 500K, vacancy concentration ranging from 0% to 1% and applied tensile strain ranging from 0 to 5%. The time evolution of defects produced during displacement cascade can be obtained where the surviving number of Frenkel pairs increases rapidly at first, then decrease and comes to stability finally. The influence of these factors on defect production can be concluded as following: The increase of PKA energy, vacancy concentration and applied tensile strain can lead to the increase of defect numbers. In contrast, the increase of temperature decreases the defect numbers. Vacancies and interstitials cluster size distributions are varied in different case. The results are meaningful to describe some microcosmic mechanisms of RPV steels in nuclear system.

Study on displacement cascade and tensile simulation by molecular dynamics: Formation and properties of point defects

2021 ◽  
pp. 2150140
Author(s):  
Pandong Lin ◽  
Junfeng Nie ◽  
Meidan Liu
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Plastic Deformation ◽  
Point Defects ◽  
Vacancy Concentration ◽  
Tensile Tests ◽  
Number Density ◽  
Displacement Cascade ◽  
Slip Bands ◽  
Dynamics Method

The molecular dynamics method is used to investigate the formation and properties of irradiation-induced damage (point defects). Displacement cascade simulations are performed to study the effects of primary knock-on atom (PKA) energy, temperature, vacancy concentration and tensile pre-strain on irradiation-induced damage in [Formula: see text]-Fe. An increase in PKA energy, vacancy concentration and tensile pre-strain can lead to an increase in defect numbers. In contrast, an increase in temperature decreases the defect numbers. After cascade collisions, tensile tests are performed to investigate the effect of point defects on mechanical properties. The yield stress and corresponding strain of irradiated Fe decrease with an increase in the number density of Frenkel pairs. Results show that irradiation accelerates damage of the internal structure, decreases the number of slip bands and increases the instability of the structure during plastic deformation.

Exploring secondary interactions and the role of temperature in moisture-contaminated polymer networks through molecular simulations

Soft Matter ◽  
2021 ◽  
Vol 17 (10) ◽  
pp. 2942-2956
Author(s):  
Rishabh D. Guha ◽  
Ogheneovo Idolor ◽  
Katherine Berkowitz ◽  
Melissa Pasquinelli ◽  
Landon R. Grace
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Temperature Variation ◽  
Polymer Networks ◽  
Molecular Simulations ◽  
Effect Of Temperature ◽  
Secondary Interactions ◽  
Dynamics Simulations ◽  
Secondary Bonding

We investigated the effect of temperature variation on the secondary bonding interactions between absorbed moisture and epoxies with different morphologies using molecular dynamics simulations.

scholarly journals How does temperature affect the dynamics of SARS-CoV-2 M proteins? Insights from Molecular Dynamics Simulations

2021 ◽  
Author(s):  
Soumya Lipsa Rath ◽  
Madhusmita Tripathy ◽  
Nabanita Mandal
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Membrane Lipids ◽  
Membrane System ◽  
Host Cells ◽  
Coarse Grained ◽  
M Protein ◽  
Effect Of Temperature ◽  
M Proteins ◽  
Dynamics Simulations

Enveloped viruses, in general, have several transmembrane proteins and glycoproteins, which assist the virus in entry and attachment onto the host cells. These proteins also play a significant role in determining the shape and size of the newly formed virus particles. The lipid membrane and the embedded proteins affect each other in non-trivial ways during the course of the viral life cycle. Unravelling the nature of the protein-protein and protein-lipid interactions, under various environmental and physiological conditions, could therefore prove to be crucial in development of therapeutics. Here, we study the M protein of SARS-CoV-2 to understand the effect of temperature on the properties of the protein-membrane system. The membrane embedded dimeric M proteins were studied using atomistic and coarse-grained molecular dynamics simulations at temperatures ranging between 10 and 50 ˚C. While temperature induced fluctuations should be monotonic, we observe a steady rise in the protein dynamics up to 40 ˚C, beyond which it surprisingly reverts back to the low temperature behaviour. Detailed investigation reveals disordering of the membrane lipids in the presence of the protein, which induces additional curvature around the transmembrane region. Coarse-grained simulations indicate temperature dependent aggregation of M protein dimers. Our study clearly indicates that the dynamics of membrane lipids and integral M protein of SARS-CoV-2 enables it to better associate and aggregate only at a certain temperature range (i.e., ~30 to 40 ˚C). This can have important implications in the protein aggregation and subsequent viral budding/fission processes.   

Investigation of the Dynamic Behavior of Railway Ballast Using Molecular Dynamics Simulations

2001 ◽  
Author(s):  
Holger Kruse ◽  
Karl Popp
Keyword(s):  
Molecular Dynamics ◽  
Initial Conditions ◽  
Contact Forces ◽  
Contact Network ◽  
Railway Ballast ◽  
Particle Layer ◽  
Dynamics Simulations ◽  
Long Term Behavior ◽  
Overlap Area

Abstract The molecular dynamics method (MD method) is a powerful tool for the investigation of granular materials like the railway ballast. The characteristics of this method are explained in detail. In contrast to a continuum description, each single stone of the ballast is taken into account. Since the ballast settlement is strongly influenced by the shape of the stones, in the two-dimensional model polygonal particles are used. These particles are surrounded by fixed boundary walls. At the top of the ballast particle layer, a single sleeper is positioned which is loaded by forces occurring at the real track. The contact forces are calculated from the overlap area of the particle geometries. The paper includes information about the sensitivity of the model behavior on initial conditions and contact law parameters. Furthermore, the contact network, the quasi-static stiffness of the ballast layer and its long-term behavior are addressed. Particular emphasis is put on the description of current difficulties and challenges in applying the MD method.

Deformation Behaviour of Single Linear Surface Defect Nickel Nanowire at Different Temperatures Studied by Molecular Dynamics Simulations

2020 ◽  
Vol 978 ◽  
pp. 428-435
Author(s):  
Krishna Chaitanya Katakam ◽  
Natraj Yedla
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Surface Defect ◽  
Deformation Behaviour ◽  
Stacking Faults ◽  
Effect Of Temperature ◽  
Dislocation Densities ◽  
Different Temperatures ◽  
Nickel Nanowire ◽  
Dynamics Simulations

The mechanical properties and deformation mechanism of nickel nanowire of dimension 100 Å (x-axis) × 1000 Å (y-axis) × 100 Å (z-axis) containing a single linear surface defect is studied at different temperatures using molecular dynamics simulations. The defect is created by deleting a row of atoms on the surface and is inclined at 25° to the loading axis. The tensile test is carried out at 0.01 K, 10 K, 100 K and 300 K temperature and 108 s-1strain rate. To determine the effect of temperature on the stress-strain curves, fracture and failure mechanism, a thorough investigation has taken place. Maximum strength of 21.26 GPa is observed for NW deformed at 0.01 K temperature and the strength decreased with increase in temperature. Through slip lines, the deformation relief pattern taken place by developing the extrusion areas along with intrusion over the surface defect area in all NWs deformed at respective temperatures. Further it is observed that fracture strains decrease with increase in temperature. After yielding, stacking faults associated with dislocations are generated by slip on all four {111} planes. Different type of dislocations with both intrinsic and extrinsic stacking faults are noticed. Out of all dislocation densities, Shockley partial dislocation densities has recorded a maximum value.

Effect of Temperature on Rheology and Nanoparticle Movements of Water Based Nanofluids by Molecular Dynamics Simulation

2016 ◽  
Author(s):  
Wenzheng Cui ◽  
Zhaojie Shen ◽  
Jianguo Yang ◽  
Shaohua Wu
Keyword(s):  
Heat Transfer ◽  
Molecular Dynamics ◽  
Cooling System ◽  
Combustion Engine ◽  
Dynamics Simulation ◽  
Effect Of Temperature ◽  
Water Based ◽  
Apparent Reason ◽  
Transfer Properties ◽  
Dynamics Method

Employing nanofluids is an innovative way to enhance heat transfer in cooling system of internal combustion engine. the reasons for the significantly enhanced heat transfer properties of nanofluids are various. On one hand, the markedly increased thermal conductivity is the most apparent reason; on the other hand, the changed rheology properties of base fluid due to the disordered movements of countless nanoparticles is even more important. Because the size scale of nanoparticles is too small, in some cases of computational simulations nanofluids is simplified as single-phase fluids. However, the influence of nanoparticles for flow behaviors of base fluids distinctly should not be ignored. By means of molecular dynamics method, a nano-scale simulation on the rheology of nanofluids could be conducted, therefore the movements of nanoparticles could be directly observed, which is conducive to reveal the influence of movements of nanoparticles for rheology of nanofluids. The present work is intended to perform a molecular dynamic simulation on the rheology of water based nanofluids. By applying temperature difference, the velocity and temperature distribution of fluid zone are calculated to evaluate heat transfer through nanofluids. Moreover, the influence of temperature for the movements of nanoparticle is discussed.

New Approach for Predicting the Long-Term Behavior of Bentonite: The Unified Method of Molecular Dynamics and Homogenization Analysis

1997 ◽  
Vol 506 ◽  
Author(s):  
K. Kawamura ◽  
Y. Ichikawa ◽  
M. Nakano ◽  
K. Kitayama ◽  
H. Kawamura
Keyword(s):  
Molecular Dynamics ◽  
Molecular Model ◽  
New Approach ◽  
Method Of Molecular Dynamics ◽  
Bulk Scale ◽  
Long Term Behavior ◽  
The Unified Method ◽  
Dynamics Method ◽  
Unified Method

ABSTRACTFor predicting the long-term behavior of bentonite, we present a new and unified simulation procedure of Molecular Dynamics Method (MD) and Homogenization Analysis (HA). The MD is applied to establish molecular-scale bentonite properties and the HA is introduced to extrapolate the molecular model to the bulk-scale continuum model.

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