NANOSCALE VOID GROWTH IN MAGNESIUM: A MOLECULAR DYNAMICS STUDY

2010 ◽  
Vol 02 (01) ◽  
pp. 191-205 ◽  
Author(s):  
SEBASTIEN GROH ◽  
ESTEBAN B. MARIN ◽  
M. F. HORSTEMEYER
Keyword(s):  
Molecular Dynamics ◽  
Strain Rate ◽  
Void Growth ◽  
Damage Evolution ◽  
Tensile Deformation ◽  
The Other ◽  
Prismatic Slip ◽  
Molecular Dynamics Calculations ◽  
Slip Planes ◽  
Crystallographic Orientations

Molecular dynamics calculations were carried out in single crystal magnesium specimens to reveal the dependence of strain rate, temperature, and orientation of the crystal on damage evolution as defined by pore growth. Two specific crystallographic orientations [0001] and [Formula: see text] were examined. During a [0001] tensile test, twin boundaries developed at the void surface leading to a constraint on the [Formula: see text] crystallographic orientation. On the other hand, during the [Formula: see text] tensile deformation, emission of shear loops in the prismatic slip planes arose when void growth initiated. Furthermore, analysis of the damage components (nucleation, growth and coalescence) revealed that a large number of small voids nucleated that rapidly grew and fractured the specimens independent of the temperature and the strain rate.

Study on the effect of temperature and strain rate on Ni2FeCrCuAl high entropy alloy: a molecular dynamics study

2021 ◽  
Vol 3 (4) ◽  
pp. 045042
Author(s):  
S Gowthaman ◽  
T Jagadeesha
Keyword(s):  
Molecular Dynamics ◽  
Strain Rate ◽  
Point Defects ◽  
Tensile Deformation ◽  
Variable Temperature ◽  
Effect Of Temperature ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Beneficial Impact ◽  
The Impact

Abstract High entropy alloy has offered significant attention in various material science applications, due to its excellent material features. In this investigation, the mechanical characteristics of Ni2FeCrCuAl High Entropy Alloy (HEA) have been examined under variable temperature and strain rates to analyze its influence over the material features of high entropy alloy through Molecular Dynamics (MD) simulation and it is stated that the formation of various point defects and dislocations are the major cause for the augmentation of tensile deformation which impacts the tensile behavior of high entropy alloy. Moreover, the Radial Distribution Function (RDF) has been examined throughout tensile deformation, to investigate the impact of applied stress over the de-bonding of various atoms and it is found that the strain rate has a greater beneficial impact over the material feature trailed by the temperature outcome, owed to its superior impact on the formation of point defects and shear strain during tensile characterization.

Molecular dynamics simulation of plastic deformation in polyethylene under uniaxial and biaxial tension

2021 ◽  
pp. 146442072110458
Author(s):  
Yi Zhang ◽  
Liang Qiao ◽  
Junming Fan ◽  
Shifeng Xue ◽  
PY Ben Jar
Keyword(s):  
Molecular Dynamics ◽  
Plastic Deformation ◽  
Molecular Dynamics Simulation ◽  
Strain Rate ◽  
Strain Softening ◽  
Biaxial Tension ◽  
Mass Density ◽  
The Other ◽  
Dynamics Simulation ◽  
Low Strain Rate

Plastic deformation of polyethylene in uniaxial and biaxial loading conditions is studied using molecular dynamics simulation. Effects of tensile strain rates from 1 × 105 to 1 × 109 s−1, and mass density in the range of 0.923–0.926 g/cm3 on mechanical behaviour and microstructure evolution are examined. Two biaxial tensile deformation modes are considered. One is through simultaneous stretching in both the x and y directions and the other sequential stretching, firstly in the x-direction and then in the y-direction while strain in the x-direction remains constant. Tangent modulus and yield stress that are determined using the stress–strain curves from the molecular dynamics simulation show a strong dependence on the deformation mode, strain rate and mass density, and all are in good agreement with results from the experimental testing, including fracture behaviour which is ductile at a low strain rate but brittle at a high strain rate. Furthermore, the study suggests that the stress–strain curves under uniaxial tension and simultaneous biaxial tension at a relatively low strain rate contain four distinguishable regions, for elastic, yield, strain softening and strain hardening, respectively, whereas under sequential biaxial tension, stress increases monotonically with the increase of strain, without noticeable yielding, strain softening or strain hardening behaviour. The molecular dynamics simulation also suggests that an increase in the strain rate enhances the possibility of cavitation. Under simultaneous biaxial tension, with the strain rate increasing from 1 × 106 to 1 × 109 s−1, the molecular dynamics simulation shows that polyethylene failure changes from a local to a global phenomenon, accompanied by a decrease of the void size and increase of uniformity in the void distribution. Under sequential biaxial tension, on the other hand, the density of the cavities is clearly reduced.

Molecular Interactions Between DNA, Cocaine and Its Metabolites

2020 ◽  
Vol 12 (3) ◽  
pp. 314-324
Author(s):  
Brunna S. M. Sousa ◽  
Igor L. P. Gonçalves ◽  
Arthur F. V. F. Reis ◽  
Abel F. G. Neto ◽  
Teodorico C. Ramalho ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
The Other ◽  
Strong Interactions ◽  
Chemical Affinity ◽  
Free Energies ◽  
Docking Simulations ◽  
Human Dna ◽  
Physical Chemical ◽  
Cocaine Metabolites ◽  
Molecular Dynamics Calculations

This present work aims to investigate the physical chemical interactions between cocaine and its metabolites with the human-DNA. The investigation was performed by molecular docking and molecular dynamics calculations, where the following cocaine metabolites were analyzed: Benzoylecgonine, Cocaethylene, Ester methylecgonine and Norcocaine. From the docking simulations we observed the hydrogen interactions most likely to occur between the drugs and DNA, whereas, through the molecular dynamics, the RMSD values were obtained and analyzed along with van der Waals, electrostatic, solvation and bind free energies between DNA and cocaine, beside its metabolites. Our results showed that the guanine in the minor groove of DNA is the nucleotide with highest chemical affinity to interact with the cocaine metabolites. On the other hand, the cocaethylene and cocaine were the drugs which presented the most stable and strong interactions with DNA, which can suggest, from molecular modeling investigations, a possible genotoxic potential of these molecules.

Anisotropic Damage Evolution for Perforated Sheet under Tensile Deformation

2016 ◽  
Vol 725 ◽  
pp. 489-494
Author(s):  
Shigeru Nagaki ◽  
Daigo Saboi ◽  
Kenta Muroi ◽  
Makoto Iizuka ◽  
Kenichi Oshita
Keyword(s):  
Plastic Deformation ◽  
Void Growth ◽  
Damage Evolution ◽  
Tensile Deformation ◽  
Yield Function ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Thermodynamic Consideration ◽  
Perforated Sheets ◽  
Growth Of Voids

It is important to formulate a constitutive equation which represents the growth of voids during plastic deformation in order to predict ductile fracture of metallic materials. For this purpose, we proposed an anisotropic Gurson’s yield function with the damage tensor, which represents the anisotropy due to the void distribution and the damage evolution was assumed isotropic for simplicity. Then we also proposed an anisotropic void growth law derived from the anisotropic Gurson’s yield function based on thermodynamic consideration. In this study we carried out the uniaxial tensile test of perforated sheets of stainless steel and aluminum alloy as the ideal two dimensional model of the damaged material and investigate the damage growth during plastic deformation. As a result, we obtained a good agreement between the experimental and the calculated void growth for both materials and it is also found that material parameters for damage evolutions are almost the same for both materials and are hardly affected by the work-hardening exponent.

scholarly journals The Effect of Temperature and Strain Rate on the Interfacial Behavior of Glass Fiber Reinforced Polypropylene Composites: A Molecular Dynamics Study

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1766 ◽  
Author(s):  
Muhan Zhang ◽  
Bingyan Jiang ◽  
Chao Chen ◽  
Dietmar Drummer ◽  
Zhanyu Zhai
Keyword(s):  
Molecular Dynamics ◽  
Strain Rate ◽  
Glass Fiber ◽  
Tensile Deformation ◽  
Interfacial Strength ◽  
Dynamics Simulation ◽  
Strain Rates ◽  
Fiber Reinforced ◽  
Interfacial Behavior ◽  
Glass Fiber Reinforced

To make better use of fiber reinforced polymer composites in automotive applications, a clearer knowledge of its interfacial properties under dynamic and thermal loadings is necessary. In the present study, the interfacial behavior of glass fiber reinforced polypropylene (PP) composites under different loading temperatures and strain rates were investigated via molecular dynamics simulation. The simulation results reveal that PP molecules move easily to fit tensile deformation at higher temperatures, resulting in a lower interfacial strength of glass fiber–PP interface. The interfacial strength is enhanced with increasing strain rate because the atoms do not have enough time to relax at higher strain rates. In addition, the non-bonded interaction energy plays a crucial role during the tensile deformation of composites. The damage evolution of glass fiber–PP interface follows Weibull’s distribution. At elevated temperatures, tensile loading is more likely to cause cohesive failure because the mechanical property of PP is lower than that of the glass fiber–PP interface. However, at higher strain rates, the primary failure mode is interfacial failure because the strain rate dependency of PP is more pronounced than that of the glass fiber–PP interface. The relationship between the failure modes and loading conditions obtained by molecular dynamics simulation is consistent with the author’s previous experimental studies.

Molecular Dynamics Study on Interfacial Fracture of Aluminum Alloy and Epoxy Resin Adhesive Subjected to Cyclic Loading

2020 ◽  
Author(s):  
Kohei Kanamori ◽  
Yoshikatsu Kimoto ◽  
Akio Yonezu
Keyword(s):  
Molecular Dynamics ◽  
Aluminum Alloy ◽  
Cyclic Loading ◽  
Strain Rate ◽  
Epoxy Resin ◽  
Adhesion Strength ◽  
Tensile Deformation ◽  
Critical Role ◽  
Interfacial Fracture ◽  
Curing Temperature

Abstract Direct bonding of metal-resin plays a critical role in jointing of dissimilar materials and the adhesion strength is known to be dependent on strain rate (loading rate) due to the strain rate sensitivity of polymeric resin. This study evaluated adhesion strength and adhesion durability against repetitive loading for the interface between aluminum alloy and epoxy resin. For experiment, a pulsed YAG laser was used to generate strong elastic waves, resulting in interfacial fracture. This method is called Laser Shock Adhesion Test (LaSAT), which enables us to evaluate impact strength of interfacial fracture. This study prepared two types of specimens with different curing temperature (20°C and 100°C). It is found that the specimen with higher temperature curing shows larger adhesion strength. Subsequently, repetitive LaSAT experiments (cyclic loading tests) were conducted to evaluate adhesion durability. This reveals that adhesion strength showed cyclic fatigue characteristics and higher curing temperature improves fatigue strength. To elucidate this mechanism at molecular level, molecular dynamics (MD) simulation was conducted for the interfacial material with epoxy resin. This study created all-atomistic model of Al2O3/epoxy resin interface, and repetitive tensile deformation was applied until delamination. It is found that the number of loading cycles to delamination was increased when the applied tensile stress was lower. It is also found that the 400K curing model showed larger adhesion strength than that of the 300K curing model. This trend is very similar with the results of LaSAT experiments. Our comprehensive study with LaSAT experiments and MD simulations evaluates adhesion strength of Al/epoxy interface and reveals its fracture mechanism.

Multiple Void Growth Simulations in the Hyper-Elastic Material

2004 ◽  
Author(s):  
Tomoaki Tsuji
Keyword(s):  
Mechanical Properties ◽  
Elastic Material ◽  
Energy Function ◽  
Void Growth ◽  
Tensile Deformation ◽  
Tensile Load ◽  
Critical Value ◽  
The Other ◽  
Hyper Elastic ◽  
Square Cell

If the hydrostatic tensile load is applied to a hyper-elastic material, the void initiates when the load exceeds the critical value. On the other hand, it is important to study multiple void growth phenomena, in order to consider the fracture by coalescence of voids. In this paper, we study the growth of multiple voids in the hyper-elastic material. The material is characterized by the energy function as the compressive material. Some experiments for the rubber, as a hyper-elastic material, are proceeded, in order to obtain these mechanical properties in the energy function. A square cell with some small voids is constructed and applied with tensile deformation by moving outer surface. The large deformation and the non-linear simulations are proceeded by using FEM. If there is only one seed, one void grows from the seed. However, when there are some seeds, we observed the void growing and the void vanishing by the influence from the other voids. The influence of the initial voids scale to the void growth is studied.

scholarly journals Anisotropic shock responses of nanoporous Al by molecular dynamics simulations

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0247172
Author(s):  
Xia Tian ◽  
Kaipeng Ma ◽  
Guangyu Ji ◽  
Junzhi Cui ◽  
Yi Liao ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Shear Stress ◽  
Molecular Dynamics Simulations ◽  
Dislocation Nucleation ◽  
Shape Evolution ◽  
Mechanical Responses ◽  
Slip Planes ◽  
Dynamics Simulations ◽  
Collapse Rate ◽  
Crystallographic Orientations

Mechanical responses of nanoporous aluminum samples under shock in different crystallographic orientations (<100>, <111>, <110>, <112> and <130>) are investigated by molecular dynamics simulations. The shape evolution of void during collapse is found to have no relationship with the shock orientation. Void collapse rate and dislocation activities at the void surface are found to strongly dependent on the shock orientation. For a relatively weaker shock, void collapses fastest when shocked along the <100> orientation; while for a relatively stronger shock, void collapses fastest in the <110> orientation. The dislocation nucleation position is strongly depended on the impacting crystallographic orientation. A theory based on resolved shear stress is used to explain which slip planes the earliest-appearing dislocations prefer to nucleate on under different shock orientations.

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