kernelcad-fea

kernelCAD — structural FEA

Declare the study in the model, run the solver, read the evidence.

const bracket = box(8, 40, 90).union(box(90, 40, 8)).fillet(4, { parallel: [0, 1, 0], concave: true });

bracket.feaStudy({
  material: 'aluminum-6061',
  fixed: { atX: 0 },                                        // bolted to the wall
  loads: [{ faces: { atZ: 8 }, force: [0, 0, -400] }],      // 400 N total, downward
  meshSize: 4,
  minSafetyFactor: 2,                                        // makes it a GATE
});

return bracket;

run_fea({ file: 'bracket.kcad.ts', output_dir: '/tmp/bracket-fea' })
// → { ok: true, summary: { minSafetyFactor: 6.10, maxVonMisesMPa: 44.28,
//     hotSpots: [{ region: '@kc[fillet_1/face/f7]', ... }],
//     trust: { meshTrusted: false, reasons: [...] },
//     refinement: { passes: [4 mm: 42.5 MPa, 3 mm: 44.3 MPa],
//                   stoppedBy: 'still-untrusted' },
//     governingField: 'away-from-supports' },
//     images: ['.../heatmap/iso.png', '.../heatmap/front.png'] }

Prerequisite: the solver toolchain

FEA shells out to two external, open-source programs. Neither is bundled.

sudo apt-get install -y calculix-ccx          # the ccx solver
python3 -m venv .fea-venv && .fea-venv/bin/pip install gmsh==4.15.2   # the mesher

Check before you design around it: fea_summary({}) reports toolchain.available plus the install hint. Override discovery with KERNELCAD_CCX and KERNELCAD_FEA_PYTHON. If apt has no calculix-ccx package, a container works equally well — mount the job directory and run ccx inside it, then point KERNELCAD_CCX at a wrapper script that does so:

#!/bin/sh
exec docker run --rm -v "$PWD:/work" -w /work <ccx-image> ccx "$@"

A missing toolchain is never a pass. run_fea and the gate both fail with fea.solver.unavailable.

Authoring the study

shape.feaStudy(spec) registers a declaration bound to that shape. It returns a handle, not a Shape — it is not part of the geometry chain.