| name | calculix-fem |
| description | Workflow skill for driving the CalculiX MCP server over .inp decks — model inspection, in-place design-variable edits, ccx solve, .dat result reading, and result_mesh.json export for the viewer. Use when an agent must run an open-source linear-static FEM analysis on CalculiX, tune section/material/load parameters, or produce a viewer-renderable result. |
CalculiX FEM
CalculiX (ccx) is an open-source FEM solver (GPLv2, no license). It reads
Abaqus-style .inp decks and writes text .dat results plus .frd field output.
ccx returns exit code 0 even on *ERROR, so never judge success by the exit
code — the solver layer checks stdout for *ERROR and requires a data row in the
.sta.
When to Use
Use this skill when an agent must run an open-source linear-static FEA analysis on
CalculiX: parse/inspect a .inp deck, tune section/material/load parameters, solve
with ccx, read .dat results, or export a viewer-renderable result. For commercial
solvers (Abaqus/Ansys), use those solvers' own skills instead.
Workflow
fea_health — confirm meshio is available and ccx is detected.parse_inp — inspect the .inp (nodes, elements, sections, materials, loads).list_design_vars_tool — list tunable variables; each carries a var_id.modify_card_tool — change a variable by var_id (pure-text, in place).run_solver_tool — submit the deck to ccx.read_results_tool — read max von Mises (self-computed), max |U|, volume, mass.export_results_tool — write result_mesh.json for the viewer.
Rules
- Units follow the
.inp working system (commonly mm-t-s-MPa). Report them.
.dat has no von Mises column and no total volume/mass — these are derived.- Never rewrite a deck with
meshio.write (it drops cards and corrupts element
types). Use modify_card_tool.
- For the deck to produce both text results and the field output the viewer needs,
include
*NODE PRINT/*EL PRINT (for .dat) and *NODE FILE/*EL FILE
(for .frd).
Example
MCP/CalculiX/examples/cantilever.inp is a public cantilever benchmark (steel
C3D8 solid bar, clamped end, transverse tip load). Hand-calc targets at P = 100 N:
tip deflection ≈ 0.8 mm, root stress ≈ 140 MPa.
