Molecular Dynamics Simulations of Pre-Crack Effects on Deformation and Failure Mechanisms for Pure Aluminum

2010 ◽  
Vol 452-453 ◽  
pp. 505-508
Author(s):  
Hua Yan Chen ◽  
Xiang Guo Zeng ◽  
Shu Sheng Xu
Keyword(s):  
Molecular Dynamics ◽  
Plastic Deformation ◽  
Crack Propagation ◽  
Pure Aluminum ◽  
Failure Mechanisms ◽  
Atomic Scale ◽  
Face Centered Cubic ◽  
Deformation And Failure ◽  
Dynamics Simulations ◽  
Fcc Structure

Micro-cracks which seriously affect the strength of metal materials always exist in metal or alloys during the manufacturing process. In order to investigate the pre-crack effects on deformation and failure mechanisms for pure aluminum at atomic scale, the plastic deformation processes of pure aluminum with face-centered cubic (fcc) crystal structure around the pre-crack tips at atomic scale were examined by means of molecular dynamics (MD) method. The Modified Embedded Atom Method (MEAM) potential was used to describe the interaction among atoms of pure aluminum. The crack propagation and failure processes for fcc structure were observed near the pre-crack tip zone. The calculation results reveal that the pre-crack blunting occurred at first, then the dislocation emitted at the pre-crack boundary and moved along with the specific direction obviously, eventually, cracks propagated along the crystallographic direction family of <110>. By means of VMD software, the graphic pictures of dislocation movement and crack propagation were obtained under different load conditions. The results and methodology given in this study are very significant for understanding more about plastic deformation and destruction at atomic scale for pure Aluminum with fcc structure.

Hybrid Continuum Mechanics and Atomistic Methods for Simulating Materials Deformation and Failure

MRS Bulletin ◽  
2007 ◽  
Vol 32 (11) ◽  
pp. 920-926 ◽  
Author(s):  
Ronald E. Miller ◽  
Ellad B. Tadmor
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Computational Cost ◽  
Atomic Scale ◽  
Molecular Statics ◽  
Deformation And Failure ◽  
Multiple Length Scales ◽  
Adequate Representation ◽  
Dynamics Simulations ◽  
Critical Regions

AbstractMany aspects of materials deformation and failure are controlled by atomic-scale phenomena that can be explored using molecular statics and molecular dynamics simulations. However, many of these phenomena involve processes on multiple length scales with the result that full molecular statics/molecular dynamics simulations of the entire system are too large to be tractable. In this review, we discuss hybrid models that perform molecular statics/molecular dynamics simulations “without all the atoms,” aimed at retaining atomistic detail at a fraction of the computational cost. These methods couple a fully atomistic model in critical regions to regions described by less-expensive continuum methods where they can provide an adequate representation of the important physics. We give an overview of the challenges such models present, with a focus on recent work to address issues of dynamics and finite (non-zero) temperature.

Molecular Dynamics Study on Interaction between Voids for Pure Aluminum

2010 ◽  
Vol 452-453 ◽  
pp. 845-848
Author(s):  
Shu Sheng Xu ◽  
Xiang Guo Zeng ◽  
Hua Yan Chen
Keyword(s):  
Molecular Dynamics ◽  
Pure Aluminum ◽  
Critical Distance ◽  
Atomic Scale ◽  
Embedded Atom Method ◽  
Face Centered Cubic ◽  
Embedded Atom ◽  
Modified Embedded Atom Method ◽  
Face Centered ◽  
The Impact

The voids in pure Aluminum always exit in the manufacturing process. The Modified Embedded Atom Method (MEAM) potential is employed in the molecular dynamics (MD) simulation at atomic scale to investigate the interaction between voids under the impact loading for pure Aluminum. The distance between the voids distributed along the loading orientation affects the failure mechanism seriously. The results show that there are 3 kinds of mechanisms with the change of the distance between voids: 1) coalescence takes place within a critical distance between voids under extra loading, 2) when the distance between voids reaches a certain value, each void cracks at 4 locations along with the slide direction <110> of face-centered cubic (fcc), respectively, 3) a stress shield zone appears when the ligament between the voids is at the size between the cases mentioned above, which brings out the phenomena that each of the voids cracks only at 2 locations, and no crack appeared at the stress shield zone.

Defect and temperature effects on the mechanical properties of kaolinite: a molecular dynamics study

Clay Minerals ◽  
2019 ◽  
Vol 54 (2) ◽  
pp. 153-159
Author(s):  
H. Yang ◽  
Z.F. Han ◽  
J. Hu ◽  
M.C. He
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Defect Density ◽  
Atomic Scale ◽  
Deformation And Failure ◽  
Defect Location ◽  
Young’S Moduli ◽  
Influence Of Temperature On ◽  
Dynamics Simulations ◽  
Location Type

AbstractMolecular dynamics simulations of different defective kaolinites under tension were performed to reveal the effects of defect location, type, density and temperature on their mechanical properties. Four types of defective kaolinite with Si vacancies were constructed. Based on the atomic-scale deformation and failure processes of defective kaolinite and its stress–strain curves, the Young's moduli and tensile strengths in three crystal directions were obtained and compared with the existing theoretical values from the literature. The defect location at each layer does not affect the mechanical properties of kaolinite and the cracks initiated at the defective sites. The atom density of each model was calculated in order to investigate the defect-type effect on the mechanical properties of kaolinite. The simulation results also showed that kaolinite exhibits brittle failure behaviour and the mechanical properties degrade significantly with increasing defect density and temperature. The influence of temperature on the mechanical properties of defective kaolinite is discussed in detail.

A Molecular Dynamics Analysis of Surface Interference and Tip Shape and Size Effects on Atomic-Scale Friction

2005 ◽  
Vol 127 (3) ◽  
pp. 513-521 ◽  
Author(s):  
J. Yang ◽  
K. Komvopoulos
Keyword(s):  
Molecular Dynamics ◽  
Friction Coefficient ◽  
Atomic Scale ◽  
Front Face ◽  
Face Centered Cubic ◽  
Friction Forces ◽  
Face Centered ◽  
Dynamics Simulations ◽  
Insight Into ◽  
Shape And Size

Molecular dynamics simulations of a rigid diamond tip sliding on a face-centered-cubic copperlike substrate were performed in order to examine the dependence of the friction coefficient on the tip–substrate interference and the shape and size of the tip. For a square-base prismatic tip, the friction force is mainly due to interactions of atoms at the front face of the tip and substrate atoms ahead of the tip, while the normal force is due to interactions of atoms at the tip base and substrate atoms under the tip. However, for a pyramidal tip, both normal and friction forces are mainly due to interactions between atoms at the front face of the tip and substrate atoms in the vicinity of the sliding tip. Consequently, the friction coefficient is either sensitive (square-base prismatic tip) or insensitive (pyramidal tip) to the tip–substrate interference distance. In addition, tip size and orientation effects on the friction coefficient were observed with square- and triangle-base prismatic tips, respectively. Lower friction coefficients were obtained with a larger base area and edge-front sliding with a triangle-base prismatic tip. The results provide insight into atomic-scale friction anisotropies due to the effects of the tip size and shape and the tip–substrate interference.

scholarly journals Molecular Dynamics Simulation of Crack Propagation in Single-Crystal Aluminum Plate with Central Cracks

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Jun Ding ◽  
Lu-sheng Wang ◽  
Kun Song ◽  
Bo Liu ◽  
Xia Huang
Keyword(s):  
Molecular Dynamics ◽  
Plastic Deformation ◽  
Crack Propagation ◽  
Strain Rate ◽  
Single Crystal ◽  
Crack Length ◽  
Crack Growth ◽  
Plastic Yield ◽  
Model Size ◽  
Dislocation Multiplication

The crack propagation process in single-crystal aluminum plate (SCAP) with central cracks under tensile load was simulated by molecular dynamics method. Further, the effects of model size, crack length, temperature, and strain rate on strength of SCAP and crack growth were comprehensively investigated. The results showed that, with the increase of the model size, crack length, and strain rate, the plastic yield point of SCAP occurred in advance, the limit stress of plastic yield decreased, and the plastic deformability of material increased, but the temperature had less effect and sensitivity on the strength and crack propagation of SCAP. The model size affected the plastic deformation and crack growth of the material. Specifically, at small scale, the plastic deformation and crack propagation in SCAP are mainly affected through dislocation multiplication and slip. However, the plastic deformation and crack propagation are obviously affected by dislocation multiplication and twinning in larger scale.

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