ICME 2017 HW2

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=Overview=
 
=Overview=
This homework takes place at the [[:Category:Nanoscale| nanoscale]] and [[:Category:Microscale| microscale]] and is separated into two parts:
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In this homework, we will bridge information from the [[:Category:Nanoscale |nanoscale]] to the [[:Category:Microscale |microscale]] by calculating the dislocation mobility drag coefficient using Molecular Dynamics, and using it to run Dislocation Dynamics simulations.
 +
There are two parts to this homework,
 +
 
 
* Molecular Dynamics (MD) using Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS)
 
* Molecular Dynamics (MD) using Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS)
 
* Dislocation Dynamics (DD) using Multiscale Dislocation Dynamics Plasticity (MDDP)
 
* 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.
+
All necessary input files and scripts are provided here or in /scratch/ICME_2017/Homework2/ . Move any of these files to your own directory (and make a backup copy) before trying to perform any simulations.
  
Write a full report that follows a journal article manuscript format (include figures and tables in the text). '''Please double-space your document'''
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Use /scratch/"Your Directory" for best results, especially if your job reads/writes much data.
  
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.
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Write a full report that follows a journal article manuscript format (include figures and tables in the text).
  
=Part 1 - Run LAMMPS for MEAM MD Calculations (upscaling for DD calibration)=
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Upon completion, submit a .pdf and .doc(x) file of your report. Be sure to also include the requested files and plots from each section of the homework.
This section of the homework requires the use of the Modified Embedded Atom Method (MEAM) to aquire dislocation mobility/drag coefficients
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<br>
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=Part 1 - Single Dislocation Mobility Calculations using MEAM=
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 <br>
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 +
==Objective==
 +
For this section, you will use the Modified Embedded Atom Method (MEAM) in Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) to acquire the dislocation mobility drag coefficient for your material.
 +
 
 +
You can obtain LAMMPS and find the user manual [http://lammps.sandia.gov/doc/Manual.html here].
 
Visit the [[LAMMPS tutorials]] page for a wide range of examples.
 
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 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:
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==Environment Setup==
: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.
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LAMMPS is an open source code and can be downloaded [http://lammps.sandia.gov here]. The source code can be easily compiled, or binary distributions are available for easy installation.
: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).  
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In addition to the software, you will need an input file, an atom position file, a post-processing script, and two files for your atomistic potential.
 +
 
 +
* The input file for this simulation is [[Velocity of an Edge Dislocation]].
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* The atom position file will be created by [[Atomistic Dislocation Generation]].
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* The [[Dislocation Velocity Ovitos Script |post-processing script]] uses [[Ovito |Ovito's ]] scripting and analysis capabilities.
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* The atomistic potential files will be from [[ICME 2017 HW1]].
 +
 
 +
==Calculating Dislocation Velocity==
 +
 
 +
===Walkthrough===
 +
 
 +
====Step 1====
 +
Generate the atomic structure
 +
 
 +
====Step 2====
 +
Run the LAMMPS Script
 +
 
 +
====Step 3====
 +
Run the post-processor and calculate the average dislocation velocity
 +
 
 +
===Homework Assignment===
 +
 
 +
<ol>
 +
<li>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.</li>
 +
<li>Run LAMMPS using the atom positions file generated in the previous step along with the LAMMPS input file for each of the following:</li>
 +
  <ol style="list-style-type: lower-latin;">
 +
    <li>Show the atom positions before the calculation illustrating the dislocation by looking at the dump.equilibration file.</li>
 +
    <li>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.</li>
 +
    <li>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. </li>
 +
    <li>Determine the drag coefficient using Equation 9.2 in the ICME for Metals textbook from the study in Part (c). </li>
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  </ol>
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</ol>
  
 
{| class="wikitable" style="width: 40%; height: 100px; margin: 1em auto 1em auto;"
 
{| class="wikitable" style="width: 40%; height: 100px; margin: 1em auto 1em auto;"
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|}
  
=Part 2 - Dislocation Dynamics Calibration=
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=Part 2 - Dislocation Dynamics=
In this section the code Multiscale Dislocation Dynamics Plasticity [[MDDP|(MDDP)]] is used. <br>
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Source code and inputs can be downloaded from this [[Media:MDDP_HW2.zip|link]]. <br>
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==Objective==
 +
In this section, you will use Multiscale Dislocation Dynamics Plasticity [[MDDP|(MDDP)]] to simulate the motion of a dislocation, thereby upscaling the dislocation mobility from the nanoscale.
 +
 
 +
==Environment Setup==
 +
 
 +
Source code and example inputs can be downloaded from this [[Media:MDDP_HW2.zip|link]]. <br>
 
Post processing instructions for MDDP are found [[MDDP Post Processing|here]].  
 
Post processing instructions for MDDP are found [[MDDP Post Processing|here]].  
  
==Assignment Sections==
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==Simulating the Motion of a Dislocation==
 +
 
 +
===Walkthrough===
 +
 
 +
====Step 1====
 +
Edit datain and create the geometry input file
 +
 
 +
====Step 2====
 +
Edit DDinput for your material parameters and mobility
 +
 
 +
====Step 3====
 +
Run MDDP
 +
 
 +
====Step 4====
 +
Post-process using TecPlot or (hopefully) Ensight or Paraview
 +
 
 +
===Homework Assignment===
 
1. Run [[MDDP|MDDP]] using the single Frank-Read source (SFRS) input. Be sure to change the data file to reflect the properties of your material as determined from LAMMPS.  
 
1. Run [[MDDP|MDDP]] using the single Frank-Read source (SFRS) input. Be sure to change the data file to reflect the properties of your material as determined from LAMMPS.  
 
:a. Generate stress-strain curves using a minimum of three (3) different mobilities.  
 
:a. Generate stress-strain curves using a minimum of three (3) different mobilities.  

Revision as of 17:18, 16 February 2017

< ICME 2017 Overview

Contents

Overview

In this homework, we will bridge information from the nanoscale to the microscale by calculating the dislocation mobility drag coefficient using Molecular Dynamics, and using it to run Dislocation Dynamics simulations. There are two parts to this homework,

  • 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 here or in /scratch/ICME_2017/Homework2/ . Move any of these files to your own directory (and make a backup copy) before trying to perform any simulations.

Use /scratch/"Your Directory" for best results, especially if your job reads/writes much data.

Write a full report that follows a journal article manuscript format (include figures and tables in the text).

Upon completion, submit a .pdf and .doc(x) file of your report. Be sure to also include the requested files and plots from each section of the homework.

Part 1 - Single Dislocation Mobility Calculations using MEAM

Objective

For this section, you will use the Modified Embedded Atom Method (MEAM) in Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) to acquire the dislocation mobility drag coefficient for your material.

You can obtain LAMMPS and find the user manual here. Visit the LAMMPS tutorials page for a wide range of examples.

Environment Setup

LAMMPS is an open source code and can be downloaded here. The source code can be easily compiled, or binary distributions are available for easy installation.

In addition to the software, you will need an input file, an atom position file, a post-processing script, and two files for your atomistic potential.

Calculating Dislocation Velocity

Walkthrough

Step 1

Generate the atomic structure

Step 2

Run the LAMMPS Script

Step 3

Run the post-processor and calculate the average dislocation velocity

Homework Assignment

  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:
    1. Show the atom positions before the calculation illustrating the dislocation by looking at the dump.equilibration file.
    2. 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.
    3. 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.
    4. Determine the drag coefficient using Equation 9.2 in the ICME for Metals textbook from the study in Part (c).
Dislocation Mobility

Part 2 - Dislocation Dynamics

Objective

In this section, you will use Multiscale Dislocation Dynamics Plasticity (MDDP) to simulate the motion of a dislocation, thereby upscaling the dislocation mobility from the nanoscale.

Environment Setup

Source code and example inputs can be downloaded from this link.
Post processing instructions for MDDP are found here.

Simulating the Motion of a Dislocation

Walkthrough

Step 1

Edit datain and create the geometry input file

Step 2

Edit DDinput for your material parameters and mobility

Step 3

Run MDDP

Step 4

Post-process using TecPlot or (hopefully) Ensight or Paraview

Homework Assignment

1. Run MDDP using the single Frank-Read source (SFRS) input. Be sure to change the data file to reflect the properties of your material 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 your material 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.

Additional Guides

ICME 2012 HW2

ICME 2013 HW2

ICME 2015 HW2

LAMMPS tutorials

MDDP Post Processing

License

By using the codes provided here you accept the the Mississippi State University's license agreement. Please read the agreement carefully before usage.

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