ICME 2013 HW3
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Contents |
Overview
- This exercise uses the hardening law parameters obtained from the previous dislocation dynamics calculations. The hardening law for slip systems is a critical aspect of crystal plasticity models and contains material related parameters which are difficult to obtain from experiments. Thus, dislocation dynamics serves as a "virtual experiment" from which the hardening parameters can be determined through a fitting routine.
- This assignment will make use of the finite element code ABAQUS
Objectives
- Downscale: Obtain hardening constants from dislocation dynamics calculations that were run in the previous homework.
- Run a finite element simulation of a single grain while varying hardening values.
- Run a finite element simulation of 20 and 180 grains while varying hardening values.
- Plot a stress-strain curve for each stress state (tension, compression, torsion).
- Plot pole figures of initial and deformed orientations
Preparation
Step 1
- Navigate to this page and locate the section for crystal plasticity finite element method (CPFEM) for aluminum.
- Copy the all the files listed to a new directory.
Step 2
- In the repository, download the single element input file "tension.inp" for ABAQUS standard. Save the file to the same directory.
Step 3
- Set up inputs for a single grain simulation
- In the UMAT file the following line needs to be edited
data filePath & /'/cavs/cmd/data1/users/qma/abaqus_xtalplas/oneelement/'/
- Replace the file path with the path to the directory that all the crystal plasticity files are saved in.
- In the ABAQUS input file the material definition needs to be edited
** MATERIALS ** *Material, name=Material-1 *Depvar 35000, *User Material, constants=2 1.,1.
- Change the number of dependent variable to NUMBER_OF_GRAINS * 70
- For a single grain depvar: 1*70=70. For 200 grains depvar: 200*70=14000
- In the texture input file, the number of grains needs to be changed
500 0 0 101.98 145.03 249.44 131.73 86.26 229.29 13.58 153.68 314.40 88.98 124.12 115.16 132.81 105.72 180.69 238.51 61.10 158.50 346.98 88.58 325.61 82.38 144.74 207.65 329.83 45.23 169.92 ... ...
- The top number (number of grains) needs to be changed to 1 (for 1 grain)
- LEAVE THE SECOND LINE IN PLACE
- Remove all but one set of Euler angles (for the one grain) and set the last number (seed number) to any value greater than the number of grains.
- Lastly, in the test.xtali input file
1 500 / crystalID (1:FCC, 2:BCC, 3:HCP), numgrn/ fcc.sx / single crystal input file 1 / ODF code (fODFCode) / 20 / multiples of inc to output texture (fODFOutInc) / texture / filename for I/O texture / ... ...
- The second number in the top most line needs to be changed to the number of grains. If when the texture file was changed (see above), it was given a new name, that new name needs to in the last line shown in place of "texture".
- In the UMAT file the following line needs to be edited
Running the Calculation
Step 1
- As with previous assignments, to avoid errors, open permission on all the files with:
chmod 755 *
Step 2
- Enter the following software setup command in a terminal
swsetup abaqus
Step 3
- The finite element simulation can be run either on Raptor or locally (very short simulation)
- Use a PBS script to submit to Raptor or enter this command into a local terminal:
abaqus job=tension user=umat_xtal.f
Output
- ABAQUS simulation output is stored in an output database file with extension ".odb".
- ODB files can be visualized and post processed in ABAQUS CAE or ABAQUS VIEWER.