ICME 2015 HW2
Contents |
Overview
This homework takes place at the nanoscale and microscale and is separated into two parts:
- Molecular Dynamics (MD) using Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS)
- Dislocation Dynamics (DD) using Multiscale Dislocation Dynamics Plasticity (MDDP)
All necessary input files and scripts are provided in the /cavs/general/Projects/ICME_2015/HW2/ directory. Move these files to your own directory (and make a backup copy) before trying to perform any simulations.
Use /scratch/"Your Directory" for best results.
Write a full report that follows a journal article manuscript format (include figures and tables in the text). Please double-space your document
Upon completion, upload a .pdf and .doc(x) file to your group folder in the ../ICME_2015/HW2/ directory. Be sure to also upload the requested files and plots from each section of the homework.
Part 1 - Run LAMMPS for MEAM MD Calculations (upscaling for DD calibration)
This section of the homework requires the use of the Modified Embedded Atom Method (MEAM) to aquire dislocation mobility/drag coefficients
Use Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) for all calculations in this section. User manual available at http://lammps.sandia.gov/doc/Manual.html
Visit the LAMMPS tutorials page for a wide range of examples.
Assignment Sections
1. Generate the atom positions file to be used for studying the mobility of an edge dislocation for nickel (FCC). A unit cell size of 100 x 60 x 2 will produce a simulation box containing ~70,000 nickel atoms.
2. Run LAMMPS using the atom positions file generated in the previous step along with the LAMMPS input file for each of the following:
- a. Show the atom positions before the calculation illustrating the dislocation by looking at the dump.all file.
- b. Use a minimum of three (3) different MEAM parameter sets based on the sensitivity analysis from HW1. Compare the position vs. time curves for each set.
- c. Study the effects of the applied shear stress on the dislocation velocity in nickel as depicted for aluminum in Figure 9.7 (a) in the ICME for Metals textbook.
- d. Determine the drag coefficient using Equation 9.2 in the ICME for Metals textbook from the study in Part (c).
| Dislocation Mobility |
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Part 2 - Dislocation Dynamics Calibration
In this section the code Multiscale Dislocation Dynamics Plasticity (MDDP) is used.
Source code and inputs can be downloaded from this link.
Post processing instructions for MDDP are found here.
Assignment Sections
1. Run MDDP using the single Frank-Read source (SFRS) input. Be sure to change the data file to reflect the properties of nickel as determined from LAMMPS.
- a. Generate stress-strain curves using a minimum of three (3) different mobilities.
- b. Illustrate the SFRS at several intervals as the dislocation loop propagates.
2. Run MDDP using the multiple Frank-Read sources (MFRS) input. Be sure to change the data file to reflect the properties of nickel as determined from LAMMPS.
- a. Generate stress-strain curves using a minimum of three (3) different mobilities. These will be used for upscaling to crystal plasticity.
- b. Illustrate the MFRS at several intervals as the dislocation loops propagate.
| Frank Read Source Operation |
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Part 3 - Room for Improvement
Improve the instructions and/or tutorials for running LAMMPS/MDDP using your experience gained from Parts 1 and 2.
Additional Guides
License
By using the codes provided here you accept the the Mississippi State University's license agreement. Please read the agreement carefully before usage.
