Usage#
As with any other simulation software, coming from a question to an answer requires
Since the materialpoint model of DAMASK can be combined with a number of different solvers for initial and boundary value problems, a further initial step is necessary:
0. Solver Selection#
The below table compares the capabilities and specifics of the three available solvers to help select the most suitable one for your problem at hand.
Feature |
Grid Solver |
Mesh Solver |
MSC Marc |
|---|---|---|---|
included in DAMASK |
|||
open source |
|||
solution method |
FEM or spectral (FFT) |
FEM |
FEM |
geometry |
regular grid |
unstructured mesh |
unstructured mesh |
boundary conditions |
mixed periodic |
tbd |
complex |
Warning
The mesh solver is under development and not yet feature complete.
1. Pre-Processing#
DAMASK Materialpoint Model#
The materialpoint model of DAMASK is configured through a material.yaml file.
Its format is documented in material.yaml.
Additional information is given in the video tutorial “Configure a DAMASK Simulation” and the Jupyter notebook on how to “Create Texture for a Dual-Phase Microstructure”.
A set of curated configuration files is available as config.tar.xz.
Geometry and Load#
The procedure for generating the geometry and setting boundary and initial conditions depends on the selected solver.
Grid Solver#
A grid solver simulation is set up with a Geometry and a Load Case file. The video tutorials “Define a Grain Structure on a Regular Grid” and “Boundary Conditions on an Infinite Body” explain the underlying ideas of these file formats. Examples are given in the Jupyter notebooks “Generate a Three-Step Load Case for the Grid Solver”, “Create a Polycrystal with Voronoi Tessellation for the Grid Solver”, and “Rescale a Grid Solver Geometry File”.
A complete simulation setup is available as grid.tar.xz.
Mesh Solver#
A mesh solver simulation is set up with a Geometry and a Load Case file.
A complete simulation setup is available as mesh.tar.xz.
MSC Marc#
An MSC Marc input deck (*.dat) can be generated manually using a text editor or with Marc Mentat, where *.proc files can be used for automatization.
DAMASK is interfaced to MSC Marc through a hypela2 user subroutine.
The link between the geometry in the input deck and the material ID in material.yaml is provided via the StateVariable 2 field.
Note
Material IDs in DAMASK are zero-based.
A complete simulation setup is available as Marc.tar.xz.
2. Running the Simulation#
In general, each solver is an executable file and can, therefore, be directly invoked from the command line prompt. The specifics of how to start a simulation, such as command line arguments or how to parallelize, depend on the selected solver.
Grid Solver#
The basic call to launch the grid solver requires as arguments the simulated Geometry and corresponding Load Case.
DAMASK_grid --load {load}.yaml --geom {grid}.vti
To parallelize the grid solver with n_threads openMP threads, the environment variable OMP_NUM_THREADS needs to be set accordingly.
OMP_NUM_THREADS={n_threads}
DAMASK_grid --load {load}.yaml --geom {grid}.vti
Parallelization over n_proc MPI processes can be accomplished with
mpiexec -n {n_proc} DAMASK_grid --load {load}.yaml --geom {grid}.vti
and will decompose the simulation domain along the z-axis into n_proc layers of approximately equal height.
Mesh Solver#
The basic call to launch the mesh solver requires as arguments the simulated Geometry and corresponding Load Case.
DAMASK_mesh --load {load}.load --geom {mesh}.msh
To parallelize the grid solver with n_threads openMP threads, the environment variable OMP_NUM_THREADS needs to be set accordingly.
OMP_NUM_THREADS={n_threads}
DAMASK_mesh --load {load}.yaml --geom {mesh}.msh
Parallelization over n_proc MPI processes can be accomplished with
mpiexec -n {n_proc} DAMASK_mesh --load {load}.yaml --geom {mesh}.msh
and will decompose the simulation domain into partitions of approximatly equal number of elements.
MSC Marc#
DAMASK is integrated into the commercial FEM software MSC Marc as a user subroutine hypela2 via DAMASK_Marc.f90.
Simulations can be started from the JOB → DAMASK menu that gets integrated into Marc Mentat during installation.
Alternatively, the DAMASK Python library contains a small wrapper that assembles the execution call and launches the MSC Marc executable.
import damask
s = damask.solver.Marc()
s.submit_job(model=modelname, job=jobname)
3. Post-Processing#
DAMASK results are stored in an HDF5-based file format. Usage examples are given in the video tutorials “Get a Custom View and Add Derived Quantities”, “Spatially-Resolved Visualization in Paraview”, and “Data Analysis: Using Matplotlib and Pandas” and Jupyter notebooks “Add Derived Field Data”, “Density Plot with Pandas”, “Plot Data per Grain with Scatter”, and “Calculate r-Value”.