ΔEVPSC: Elasto-Visco-Plastic Self-Consistent polycrystal model

ΔEVPSC (delta-EVPSC) is a Fortran implementation of an elasto-visco-plastic self-consistent (EVPSC) polycrystal plasticity model based on a single homogeneous effective medium (HEM). It can be run as a stand-alone program or used as a material subroutine in the Abaqus finite element solver.

EVPSC is derived from the visco-plastic self-consistent (VPSC) code of R. A. Lebensohn and C. N. Tome (Los Alamos National Laboratory). See NOTICE for details.

Features

• Stand-alone EVPSC simulations under mixed stress/strain boundary conditions [1, 2]
  • A single HEM accounts for both elasticity and visco-plasticity, which is computationally faster than EVPSC formulations that use two separate HEMs [1, 3]
  • Slip and twinning; Voce and dislocation-density-based hardening
  • Texture and grain-shape evolution
• Abaqus/Standard UMAT interface (umat/src/evpsc_incr) that shares the core subroutines with the stand-alone program [2]
  • Note: the Abaqus/Explicit VUMAT (vumat.f) is not complete and does not work yet. It is included only as a placeholder for future development.
• Forming limit diagram (FLD) prediction based on the Marciniak-Kuczynski approach [4]

Repository layout

Path	Contents
src/vpsc_src/	Fortran source of the stand-alone EVPSC program and the single-crystal file parser (parser_fnsx.f)
umat/src/evpsc_incr/	Abaqus UMAT interface (VUMAT: placeholder only)
umat/src/pheno/	Phenomenological constitutive models for Abaqus
pyscripts/	Helper scripts (gen_dim.py, build.py, ...)
*.mk, Makefile	Build rules

Requirements

• A Fortran compiler: GNU Fortran (gfortran) is used for development of the stand-alone program; the Intel Fortran compiler is used for Abaqus simulations.

• GNU Make

• Python 3 with numpy, matplotlib and chardet. The python command must start Python 3, because the scripts call each other through python.

  pip install numpy matplotlib chardet

• For plotting and some options of the Abaqus driver (umat/src/evpsc_incr/run.py), the Python packages MP (mpl-lib3) and TX (texture3)

• Abaqus/Standard for finite element simulations

Build the stand-alone program

1. Generate the dimension file src/vpsc_src/parameters.dim, which sets the maximum array sizes (phases, grains, deformation modes, etc.):

   python pyscripts/gen_dim.py -o src/vpsc_src/parameters.dim \
       --nphmx 1 --ngrmx 2000 --nmodmx 2 --ntwmmx 0 --nsysmx 24 --ntwsmx 0

   Run python pyscripts/gen_dim.py -h for all options. Alternatively, copy one of the provided examples:

   cp src/vpsc_src/parameters_rex.dim src/vpsc_src/parameters.dim

2. Compile:

   make -j evpsc

   This creates the executable evpsc. Use make evpsc ENV=debug for a build with run-time checks.

The input files follow the VPSC conventions (vpsc7.in, single-crystal and texture files). For a description of the VPSC input format, see Chapter 5 of Tome and Lebensohn (2023) [6].

Run the Abaqus example

A one-element Abaqus/Standard example is in umat/src/evpsc_incr/. After generating src/vpsc_src/parameters.dim (step 1 above):

cd umat/src/evpsc_incr
python run.py --fn umat_example.in --ngrs 100 --cpus 1

See umat/src/evpsc_incr/README.md for the input file format, the example files and the options of run.py.

License

EVPSC is released under the BSD 3-Clause License; see LICENSE. Portions derived from VPSC are (c) 2022 Triad National Security, LLC, also under the BSD 3-Clause License; see NOTICE.

How to cite

If you use EVPSC, please cite Ref. [1] and, for the finite element interface, Ref. [2]. Citation metadata is in CITATION.cff.

References

1. Y. Jeong, C. N. Tome, An efficient elasto-visco-plastic self-consistent formulation: Application to steel subjected to loading path changes, International Journal of Plasticity 135 (2020) 102812. https://doi.org/10.1016/j.ijplas.2020.102812
2. Y. Jeong, B. Jeon, C. N. Tome, Finite element analysis using an incremental elasto-visco-plastic self-consistent polycrystal model: FE simulations on Zr and low-carbon steel subjected to bending, stress-relaxation, and unloading, International Journal of Plasticity 147 (2021) 103110. https://doi.org/10.1016/j.ijplas.2021.103110
3. B. Jeon, Y. Jeong, C. N. Tome, A critical discussion of elasto-visco-plastic self-consistent (EVPSC) models, Journal of Materials Research and Technology 33 (2024) 7596-7609. https://doi.org/10.1016/j.jmrt.2024.11.043
4. Y. Jeong, M.-S. Pham, M. Iadicola, A. Creuziger, T. Foecke, Forming limit predictions using a self-consistent crystal plasticity framework: a case study for body-centered cubic materials, Modelling and Simulation in Materials Science and Engineering 24 (2016) 055005. https://doi.org/10.1088/0965-0393/24/5/055005
5. R. A. Lebensohn, C. N. Tome, A self-consistent anisotropic approach for the simulation of plastic deformation and texture development of polycrystals: Application to zirconium alloys, Acta Metallurgica et Materialia 41 (1993) 2611-2624. https://doi.org/10.1016/0956-7151(93)90130-K
6. C. N. Tome, R. A. Lebensohn, Material Modeling with the Visco-Plastic Self-Consistent (VPSC) Approach: Theory and Practical Applications, Elsevier (2023).

Contact

Youngung Jeong, Department of Materials Science and Metallurgy, Changwon National University, Republic of Korea (youngung.github.io)