Crack Growth and Propagation in Metallic Alloys

1995 ◽  
Vol 409 ◽  
Author(s):  
W. C. Morrey ◽  
L. T. Wille
Keyword(s):  
Large Scale ◽  
Critical Strain ◽  
Cleavage Plane ◽  
Crack Tip ◽  
Metallic Alloys ◽  
Propagation Direction ◽  
Dynamics Simulation ◽  
Parallel Computer ◽  
Massively Parallel ◽  
Tip Position

AbstractUsing large-scale molecular dynamics simulation on a massively parallel computer, we have studied the initiation of cracking in a Monel-like alloy of Cu-Ni. In a low temperature 2D sample, fracture from a notch starts at a little beyond 2.5% critical strain when the propagation direction is perpendicular to a cleavage plane. We discuss a method of characterizing crack tip position using a measure of area around the crack tip.

Compressible Flow Simulations on a Massively Parallel Computer

1991 ◽  
Vol 02 (01) ◽  
pp. 430-436
Author(s):  
ELAINE S. ORAN ◽  
JAY P. BORIS
Keyword(s):  
Compressible Flow ◽  
Chemical Reactions ◽  
Large Scale ◽  
Model Development ◽  
Time Dependent ◽  
Parallel Computer ◽  
Massively Parallel ◽  
Parallel Solution ◽  
Flow Simulations ◽  
Connection Machine

This paper describes model development and computations of multidimensional, highly compressible, time-dependent reacting on a Connection Machine (CM). We briefly discuss computational timings compared to a Cray YMP speed, optimal use of the hardware and software available, treatment of boundary conditions, and parallel solution of terms representing chemical reactions. In addition, we show the practical use of the system for large-scale reacting and nonreacting flows.

Nano-Indentation Simulation Study Based on Parallel Computing

2012 ◽  
Vol 500 ◽  
pp. 696-701
Author(s):  
Ying Zhu ◽  
Sen Song ◽  
Ling Ling Xie ◽  
Shun He Qi ◽  
Qian Qian Liu
Keyword(s):  
Molecular Dynamics ◽  
Parallel Computing ◽  
Molecular Dynamics Simulation ◽  
Large Scale ◽  
Dynamics Simulation ◽  
Parallel Computer ◽  
Nano Indentation ◽  
Simulation Results ◽  
The Impact ◽  
Simulation Time

This method of parallel computing into nanoindentation molecular dynamics simulation (MDS), the author uses a nine-node parallel computer and takes the single crystal aluminum as the experimental example, to implement the large-scale process simulation of nanoindentation. Compared the simulation results with experimental results is to verify the reliability of the simulation. The method improves the computational efficiency and shortens the simulation time and the expansion of scale simulation can significantly reduce the impact of boundary conditions, effectively improve the accuracy of the molecular dynamics simulation of nanoindentation.

Molecular dynamics simulation of the crystallization of liquid GaAs nanoparticles

2019 ◽  
Vol 33 (31) ◽  
pp. 1950392
Author(s):  
Qian Chen ◽  
Yao Zhou ◽  
Zean Tian ◽  
Tinghong Gao ◽  
Ting Xiao ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Coordination Number ◽  
Large Scale ◽  
Crystallization Process ◽  
Surface Effect ◽  
Dynamics Simulation ◽  
Massively Parallel ◽  
Zinc Blende ◽  
Zinc Blende Structure ◽  
Number Form

The GaAs nanoparticles crystallization process was simulated with the molecular dynamics package large-scale atomic/molecular massively parallel simulator (LAMMPS). The results show that due to the surface effect, GaAs nanoparticles have a low melting temperature and poor order, and that their atomic thermal vibration at high temperatures is more severe than that of GaAs crystals. The crystallization process of GaAs nanoparticles begins at 970 K and generally completes at 920 K. Atoms with coordination number 3 or 4 form honeycomb-like defective (111) faces of zinc-blende structure on the surface; and atoms with a higher coordination number form two-dimensional dense structures at the subsurface.

scholarly journals A Linked-Cell Domain Decomposition Method for Molecular Dynamics Simulation on a Scalable Multiprocessor

1992 ◽  
Vol 1 (2) ◽  
pp. 153-161 ◽  
Author(s):  
L.H. Yang ◽  
E.D. Brooks III ◽  
J. Belak
Keyword(s):  
Molecular Dynamics ◽  
Large Scale ◽  
Domain Decomposition Method ◽  
Dynamics Simulation ◽  
Parallel Computer ◽  
Interprocessor Communication ◽  
Programming Paradigm ◽  
C Preprocessor ◽  
Large Scale Simulations ◽  
Cell Data

A molecular dynamics algorithm for performing large-scale simulations using the Parallel C Preprocessor (PCP) programming paradigm on the BBN TC2000, a massively parallel computer, is discussed. The algorithm uses a linked-cell data structure to obtain the near neighbors of each atom as time evoles. Each processor is assigned to a geometric domain containing many subcells and the storage for that domain is private to the processor. Within this scheme, the interdomain (i.e., interprocessor) communication is minimized.

scholarly journals HYPER-SYSTOLIC PROCESSING ON APE100/QUADRICS: n2-LOOP COMPUTATIONS

1996 ◽  
Vol 07 (04) ◽  
pp. 485-501 ◽  
Author(s):  
THOMAS LIPPERT ◽  
GERO RITZENHÖFER ◽  
UWE GLAESSNER ◽  
HENNING HOEBER ◽  
ARMIN SEYFRIED ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Body Problem ◽  
Three Dimensional ◽  
Dynamics Simulation ◽  
Parallel Computer ◽  
Massively Parallel ◽  
Interprocessor Communication ◽  
Communication Costs ◽  
N Body Problem ◽  
Performance Gains

We investigate the performance gains from hyper-systolic implementations of n2-loop problems on the massively parallel computer Quadrics, exploiting its three-dimensional interprocessor connectivity. For illustration we study the communication aspects of an exact molecular dynamics simulation of n particles with Coulomb (or gravitational) interactions. We compare the interprocessor communication costs of the standard-systolic and the hyper-systolic approaches for various granularities. We predict gain factors as large as three on the Q4 and eight on the QH4 and measure actual performances on these machine configurations. We conclude that it appears feasible to investigate the thermodynamics of a full gravitating n-body problem with O(16.000) particles using the new method on a QH4 system.

scholarly journals TRILLION-ATOM MOLECULAR DYNAMICS BECOMES A REALITY

2008 ◽  
Vol 19 (09) ◽  
pp. 1315-1319 ◽  
Author(s):  
TIMOTHY C. GERMANN ◽  
KAI KADAU
Keyword(s):  
Molecular Dynamics ◽  
Large Scale ◽  
Shear Instability ◽  
Dynamics Simulation ◽  
Massively Parallel ◽  
Lennard Jones ◽  
Simple Cubic ◽  
Simple Cubic Lattice ◽  
Future Potential ◽  
Large Scale Simulations

By utilizing the molecular dynamics code SPaSM on Livermore's BlueGene/L architecture, consisting of 212 992 IBM PowerPC440 700 MHz processors, a molecular dynamics simulation was run with one trillion atoms. To demonstrate the practicality and future potential of such ultra large-scale simulations, the onset of the mechanical shear instability occurring in a system of Lennard-Jones particles arranged in a simple cubic lattice was simulated. The evolution of the instability was analyzed on-the-fly using the in-house developed massively parallel graphical object-rendering code MD_render.

Large-Scale Molecular Dynamics Investigation of Nanoscale Laser Material Processing

2003 ◽  
Author(s):  
Xinwei Wang ◽  
Hua Zhu
Keyword(s):  
Molecular Dynamics ◽  
Large Scale ◽  
Axial Direction ◽  
Sample Surface ◽  
Dynamics Simulation ◽  
Parallel Computer ◽  
Scanning Tunneling ◽  
Laser Material Processing ◽  
Surface Nanostructures ◽  
Nanoscale Manufacturing

In this work, large-scale molecular dynamics simulation is conducted to explore nanoscale manufacturing with laser-assisted scanning tunneling microscope. Employing a super parallel computer, more than 100 million atoms are modeled to provide substantial details about how the localized thermal and mechanical perturbations result in surface nanostructures. It is found that thermal equilibrium cannot be established due to the small number of atoms. Extremely localized stress accumulation beneath the sample surface results in an explosion of the melted/vaporized material, leaving a nanoscale hole on the sample surface. Normal and shear stress development is observed. Stress propagation in space is strongly influenced by the anisotropic nature of the crystal. The high pressure in the melted/vaporized region pushes the melt adjacent to the solid to move, thereby forming a protrusion at the edge of the hole. More importantly, visible structural destruction is observed in the region close to the bottom of the sample. These destructions are along the direction of 45 degrees with respect to the axial direction, and are attributed to the strong tensile stress. Atomic dislocation is observed in the destructed regions.

Massively Parallel Molecular Dynamics Simulations of Two-dimensional Materials at High Strain Rates

1992 ◽  
Vol 291 ◽  
Author(s):  
Norman J. Wagner ◽  
Brad Lee Holian
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Large Scale ◽  
Spall Strength ◽  
Computer Experiments ◽  
Dislocation Dynamics ◽  
Parallel Computer ◽  
Massively Parallel ◽  
Connection Machine ◽  
Dynamics Simulations

ABSTRACTLarge scale molecular dynamics simulations on a massively parallel computer are performed to investigate the mechanical behavior of 2-dimensional materials. A model embedded atom many- body potential is examined, corresponding to “ductile” materials. A parallel MD algorithm is developed to exploit the architecture of the Connection Machine, enabling simulations of > 106atoms. A model spallation experiment is performed on a 2-D triagonal crystal with a well-defined nanocrystalline defect on the spall plane. The process of spallation is modelled as a uniform adiabatic expansion. The spall strength is shown to be proportional to the logarithm of the applied strain rate and a dislocation dynamics model is used to explain the results. Good predictions for the onset of spallation in the computer experiments is found from the simple model. The nanocrystal defect affects the propagation of the shock front and failure is enhanced along the grain boundary.

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