frd2vtu

Convert CalculiX binary .frd files to VTK .vtu files for ParaView and other VTK tools. Inspired by ccx2paraview.

Overview

frd2vtu reads CalculiX binary FRD output (from *element output / *node output) and writes VTK unstructured grids with field data per timestep. Multiple files can be converted in parallel.

Installation

pip install frd2vtu

Development install:

uv pip install -e ".[dev]"

Usage

Convert one or more FRD files (parallel by default; output goes next to each input unless --output-dir is set):

frd2vtu convert model.frd
frd2vtu convert run1.frd run2.frd --output-dir ./vtu
frd2vtu convert *.frd --no-parallel

Prepare a CalculiX .inp for binary FRD output (*node file / *el file → *node output / *element output):

frd2vtu iprep model.inp
frd2vtu iprep model.inp --output-dir ./prepared

Plot VTU point arrays (writes a PNG beside each file):

frd2vtu_plot model.vtu
frd2vtu_plot a.vtu b.vtu --no-parallel

CLI help is tree-shaped; export the command schema as JSON:

frd2vtu --help
frd2vtu --json

Python API

from frd2vtu import frdbin2vtu, frd2vtu

grid = frdbin2vtu("model.frd", output_dir="out/")
frd2vtu(["run1.frd", "run2.frd"], parallel=True, output_dir="out/")

Examples

Screenshots from the CalculiX test directory:

License

MIT — see LICENSE.

Test coverage

Tested against binary CalculiX FRD files in test/frds/ (ASCII header-only stubs are omitted). Regenerate with make readme-coverage.

142 files

File	Status
acou4	✅
acou5	✅
acouquad	✅
anipla2	✅
anipla3	✅
anipla4	✅
anipla_nl_dy_exp	✅
anipla_nl_dy_imp	✅
anipla_nl_st	✅
artery3	✅
artery4	✅
artery5	✅
b31	✅
ball	✅
beam10psmooth	✅
beam8pjc	✅
beam_sens_freq_coord2	✅
beam_sens_freq_coord3	✅
beam_sens_ps13	✅
beam_sens_stress_coord1	✅
beam_sens_stress_coord1_explicit	✅
beam_sens_stress_coord1_implicit	✅
beam_sens_stress_coord2	✅
beamcr3	✅
beamexpdy1	✅
beamf	✅
beamf3	✅
beamfrdread	✅
beamfsms	✅
beamhtfcnu	✅
beamimpdy1	✅
beamimpdy1nodirect	✅
beamimpdy2	✅
beamnldy	✅
beamnldye	✅
beamnldye20	✅
beamnldyems	✅
beamnldyeortho	✅
beamnldynodirect	✅
beamnldyp	✅
beamnldype	✅
beamp	✅
beamp1rotate	✅
beamp2	✅
beamp3	✅
beamp_ciarlet	✅
beamperror	✅
beamprb	✅
beamt	✅
beamwrite3	✅
boxprofile	✅
boxprofile2	✅
changecontacttype1	✅
changecontacttype2	✅
changesolidsection	✅
channeljoint1a	✅
circ10p	✅
circ10pcent	✅
concretebeam	✅
contact11	✅
contact12	✅
contact15	✅
contact15lin	✅
contact16	✅
contact19	✅
contact2	✅
contdamp1	✅
contdamp2	✅
coupling13	✅
coupling14	✅
cube2	✅
cubef2f3	✅
cubenewt	✅
cyl	✅
dashpot5	✅
dashpot6	✅
disconnect	✅
dyncube	✅
dyncubeexp	✅
equrem1	✅
equrem2	✅
equrem3	✅
equrem4	✅
gap2	✅
green1	✅
impdyn	✅
induction	✅
largerot1	✅
largerot2	✅
largerot3	✅
largerot4	✅
largerot5	✅
leifer1	✅
leifer2	✅
membrane1	✅
membrane3	✅
mohr1	✅
mohr2	✅
networkmpc2	✅
oneel	✅
oneeltruss	✅
opt1	✅
opt1dp	✅
opt2	✅
pendel	✅
pipe2	✅
planestrain	✅
planestrain2	✅
planestress3	✅
planestress3dsens	✅
planestress4	✅
plate2dmass	✅
plate2dpeeq	✅
pret1	✅
pret4	✅
pret5	✅
pret6	✅
primaryair	✅
section	✅
segmentsmooth	✅
segmentsmooth2	✅
segmentunsmooth	✅
sens3d	✅
sensitivity_VII	✅
shell1	✅
shell3	✅
shell5	✅
shell6	✅
shell6rot2	✅
shell7	✅
shell7rot	✅
shell7rot2	✅
simplebeam	✅
simplebeampipe5	✅
square	✅
tempdiscon	✅
testmortar	✅
thermomech	✅
truss	✅
truss2	✅
uprofile	✅
zerovel	✅