ICME 2017 HW2
- 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 /scratch/ICME_2017/Homework2/ 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_2017/Homework2/ 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.
1. Generate the atom positions file to be used for studying the mobility of an edge dislocation for your FCC or BCC material. A unit cell size of 100 x 60 x 2 will produce a simulation box containing ~70,000 atoms for an FCC structure.
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 your material compared to aluminum as 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).
Part 2 - Dislocation Dynamics Calibration
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|
Part 3 - Room for Improvement
Improve the instructions and/or tutorials for running LAMMPS/MDDP using your experience gained from Parts 1 and 2.
By using the codes provided here you accept the the Mississippi State University's license agreement. Please read the agreement carefully before usage.