med2limit

Convert Code_Aster MED/RMED simulation results into LIMIT .linp / .lui input files for fatigue analysis.

Features

• Shell workflows (DKT elements: S3, S4) with REPLO/CARCOQUE handling
• Linear solid workflows (C3D8 / HEXA8, C3D6 / PENTA6) with validated LIMIT node ordering
• Multi-step / multi-increment displacement and stress transfer
• Optional shell orientation file, or read directly from IMPR_CONCEPT-embedded result file
• Automatic detection of shell support level (works for shell-only and mixed hexa+shell models)

Code_aster Requirement

• Identify weld groups as Group_NO (not Group_MA), 1 node set per weld
• For shell element, extract top/bottom stresses as:

SIEF_SUP=POST_CHAMP(RESULTAT=RESU,
                    EXTR_COQUE=_F(NOM_CHAM='SIEF_ELNO',
                                  NUME_COUCHE=1,
                                  NIVE_COUCHE='SUP',),);

SIEF_INF=POST_CHAMP(RESULTAT=RESU,
                    EXTR_COQUE=_F(NOM_CHAM='SIEF_ELNO',
                                  NUME_COUCHE=1,
                                  NIVE_COUCHE='INF',),);

• For shell element, extract orientation/tichkness as:

IMPR_CONCEPT(FORMAT='MED',
             UNITE=80, --> Same unit as your results or in a dedicated file
             CONCEPT=(_F(CARA_ELEM=Elem,
                         REPERE_LOCAL='ELEM',
                         MODELE=Modell,),),)                                  

Installation

Install med2limit with pip into a virtual python environnement (venv):

python3 -m venv .venv
source .venv/bin/activate
pip install med2limit

Usage

Command line

From 01_exemple in folder:

med2limit/exemples/data

med2limit 01_exemple.rmed output.linp output.lui --groups "Shell1,Shell2" --nsets "WeldNo"

With separate orientation file:

med2limit 01_exemple.rmed output.linp output.lui 01_carcoc.rmed --groups "Shell1,Shell2" --nsets "WeldNo"

01_exemple

Code_aster Shell-Shell geometry successfully imported in LIMIT Software

02_exemple

Code_aster Solid-Shell geometry successfully imported in LIMIT Software

Python API

from med2limit import MEDToLimitConverter

conv = MEDToLimitConverter(
    med_filename="LIMIT1.rmed",
    linp_filename="out.linp",
    lui_filename="out.lui",
    active_groups=["Shell1", "Shell2"],
    active_nsets=["WeldNo"],
)
conv.convert()

Package layout

med2limit/
├── element_types.py   # MED↔LIMIT type mapping + helpers (pure)
├── reader.py          # MED file open + field lookup
├── mesh.py            # nodes, elements, GROUP_MA, GROUP_NO
├── fields.py          # DEPL + SIEF over all timesteps
├── orientation.py     # REPLO + CARCOQUE (embedded or separate)
├── filter.py          # active group selection + shell metadata mapping
├── result_mapper.py   # per-timestep stress/displacement mapping
├── writer.py          # .linp + .lui output
├── converter.py       # orchestrator (step_1 .. step_6 + convert)
└── cli.py             # CLI + in-script config

Testing

pytest                      # all tests
pytest tests/test_element_types.py   # one module

Known limitations

• Quadratic solids (C3D10, C3D15, C3D20) — node ordering not yet validated in LIMIT
• Shell elsets with mixed thicknesses use the most-frequent value (with warning)

Acknowledgments

Special thanks to Tobias and Nikolaus for their feedback as early adopters and their patience during the iterative development of the converter.