ICME 2013 HW3

From EVOCD
Jump to: navigation, search

< Back to ICME 2013 Course Overview

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".

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.
Personal tools
Namespaces

Variants
Actions
home
Materials
Material Models
Design
Resources
Projects
Education
Toolbox