JAX 3D Modal Analysis
Full 3D tetrahedral FEM eigenvalue solver for ribbed membrane resonators.
Complements fem-analysis (2D Kirchhoff plate approximation) by accounting for
3D volumetric effects, frame stiffness, and out-of-plane deformation.
Usage
python3 {baseDir}/scripts/jax_modal_analysis.py \
--stl /path/to/membrane.stl \
--material '{"E_Pa":3e9,"nu":0.35,"rho_kg_m3":1500}' \
--num-modes 12 \
--solver-backend jax-iterative \
--stl-length-scale 1e-3 \
--target-freq-min 2000 \
--target-freq-max 8000 \
--output-dir /tmp/jax_modal_results
Arguments
| Flag |
Type |
Default |
Description |
--stl |
path |
required |
Binary STL file (mm units assumed) |
--material |
JSON str |
required |
{"E_Pa":3e9,"nu":0.35,"rho_kg_m3":1500} |
--num-modes |
int |
12 |
Number of modes to compute |
--solver-backend |
str |
jax-iterative |
arpack, jax-iterative, or jax-xla |
--stl-length-scale |
float |
1e-3 |
Scale factor to convert STL units → metres |
--target-freq-min |
float |
2000 |
Lower bound of target frequency band (Hz) |
--target-freq-max |
float |
8000 |
Upper bound of target frequency band (Hz) |
--output-dir |
path |
auto |
Directory for all output files |
Output JSON
{
"stl_path": "/path/to/membrane.stl",
"topology": "v1_cricket_fine",
"num_modes_computed": 12,
"eigenfrequencies_hz": [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 2153.0, 2388.1, ...],
"eigenfrequencies_khz": [0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 2.153, 2.388, ...],
"modes_in_range_hz": [2153.0, 2388.1, 5401.2, 6890.3],
"modes_in_range_khz": [2.153, 2.388, 5.401, 6.890],
"target_range_hz": [2000, 8000],
"target_range_khz": [2.0, 8.0],
"target_range_pass": true,
"solver_backend": "arpack",
"output_dir": "/tmp/jax_modal_results/v1_cricket_fine_...",
"summary_png": "/tmp/.../summary_figures/modal_run_summary.png",
"csv_path": "/tmp/.../modal_comprehensive_report.csv",
"mesh_vtu": "/tmp/.../mesh/volume_mesh.vtu"
}
Chaining with fem-analysis
fem-analysis and jax-modal-analysis are complementary, not alternatives:
| Skill |
Model |
Speed |
Best for |
fem-analysis |
2D Kirchhoff plate |
~1 s |
Fast screening, flat membranes |
jax-modal-analysis |
3D tetrahedral FEM |
30–120 s |
Full 3D validation, ribbed/curved geometries |
Recommended workflow:
- Run
fem-analysis to shortlist candidates (fast 2D pass/fail)
- Run
jax-modal-analysis on shortlisted STLs for full 3D validation
1---2name: jax-modal-analysis3description: 3D tetrahedral FEM modal analysis of a membrane STL. Takes a binary STL (mm units) + material properties JSON, repairs surface mesh, generates tetrahedral volume mesh via TetGen, assembles 3D stiffness/mass matrices with jax-fem, solves the generalised eigenvalue problem, and reports eigenfrequencies + mode shapes. Returns artifact JSON with eigenfrequencies_hz, eigenfrequencies_khz, modes_in_range, target_range_pass, and paths to summary PNG and CSV.4---56# JAX 3D Modal Analysis78Full 3D tetrahedral FEM eigenvalue solver for ribbed membrane resonators.9Complements `fem-analysis` (2D Kirchhoff plate approximation) by accounting for103D volumetric effects, frame stiffness, and out-of-plane deformation.1112## Usage1314```bash15python3 {baseDir}/scripts/jax_modal_analysis.py \16 --stl /path/to/membrane.stl \17 --material '{"E_Pa":3e9,"nu":0.35,"rho_kg_m3":1500}' \18 --num-modes 12 \19 --solver-backend jax-iterative \20 --stl-length-scale 1e-3 \21 --target-freq-min 2000 \22 --target-freq-max 8000 \23 --output-dir /tmp/jax_modal_results24```2526## Arguments2728| Flag | Type | Default | Description |29|------|------|---------|-------------|30| `--stl` | path | required | Binary STL file (mm units assumed) |31| `--material` | JSON str | required | `{"E_Pa":3e9,"nu":0.35,"rho_kg_m3":1500}` |32| `--num-modes` | int | 12 | Number of modes to compute |33| `--solver-backend` | str | `jax-iterative` | `arpack`, `jax-iterative`, or `jax-xla` |34| `--stl-length-scale` | float | `1e-3` | Scale factor to convert STL units → metres |35| `--target-freq-min` | float | 2000 | Lower bound of target frequency band (Hz) |36| `--target-freq-max` | float | 8000 | Upper bound of target frequency band (Hz) |37| `--output-dir` | path | auto | Directory for all output files |3839## Output JSON4041```json42{43 "stl_path": "/path/to/membrane.stl",44 "topology": "v1_cricket_fine",45 "num_modes_computed": 12,46 "eigenfrequencies_hz": [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 2153.0, 2388.1, ...],47 "eigenfrequencies_khz": [0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 2.153, 2.388, ...],48 "modes_in_range_hz": [2153.0, 2388.1, 5401.2, 6890.3],49 "modes_in_range_khz": [2.153, 2.388, 5.401, 6.890],50 "target_range_hz": [2000, 8000],51 "target_range_khz": [2.0, 8.0],52 "target_range_pass": true,53 "solver_backend": "arpack",54 "output_dir": "/tmp/jax_modal_results/v1_cricket_fine_...",55 "summary_png": "/tmp/.../summary_figures/modal_run_summary.png",56 "csv_path": "/tmp/.../modal_comprehensive_report.csv",57 "mesh_vtu": "/tmp/.../mesh/volume_mesh.vtu"58}59```6061## Chaining with fem-analysis6263`fem-analysis` and `jax-modal-analysis` are **complementary**, not alternatives:6465| Skill | Model | Speed | Best for |66|-------|-------|-------|----------|67| `fem-analysis` | 2D Kirchhoff plate | ~1 s | Fast screening, flat membranes |68| `jax-modal-analysis` | 3D tetrahedral FEM | 30–120 s | Full 3D validation, ribbed/curved geometries |6970Recommended workflow:711. Run `fem-analysis` to shortlist candidates (fast 2D pass/fail)722. Run `jax-modal-analysis` on shortlisted STLs for full 3D validation
lamm-mit