Fracture simulations via massively parallel molecular dynamics
- Los Alamos National Lab., NM (United States)
- IBM Research Div., San Jose, CA (United States). Almaden Research Center
- Texas Univ., El Paso, TX (United States)
Fracture simulations at the atomistic level have heretofore been carried out for relatively small systems of particles, typically 10,000 or less. In order to study anything approaching a macroscopic system, massively parallel molecular dynamics (MD) must be employed. In two spatial dimensions (2D), it is feasible to simulate a sample that is 0.1 {mu}m on a side. We report on recent MD simulations of mode I crack extension under tensile loading at high strain rates. The method of uniaxial, homogeneously expanding periodic boundary conditions was employed to represent tensile stress conditions near the crack tip. The effects of strain rate, temperature, material properties (equation of state and defect energies), and system size were examined. We found that, in order to mimic a bulk sample, several tricks (in addition to expansion boundary conditions) need to be employed: (1) the sample must be pre-strained to nearly the condition at which the crack will spontaneously open; (2) to relieve the stresses at free surfaces, such as the initial notch, annealing by kinetic-energy quenching must be carried out to prevent unwanted rarefactions; (3) sound waves emitted as the crack tip opens and dislocations emitted from the crack tip during blunting must be absorbed by special reservoir regions. The tricks described briefly in this paper will be especially important to carrying out feasible massively parallel 3D simulations via MD.
- Research Organization:
- Los Alamos National Lab., NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 10185444
- Report Number(s):
- LA-UR--93-3184; CONF-931121--22; ON: DE93040159
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360102
665000
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
99 GENERAL AND MISCELLANEOUS
990200
BOUNDARY CONDITIONS
CALCULATION METHODS
COMPUTER CALCULATIONS
CRACK PROPAGATION
CRYSTALS
DYNAMICS
FRACTURE MECHANICS
FRACTURES
FRAGMENTATION
KINETICS
MATHEMATICS AND COMPUTERS
METALS
PHYSICS OF CONDENSED MATTER
STATISTICAL MECHANICS
STRAIN RATE
STRUCTURE AND PHASE STUDIES