A property-registry contract for retrieve-or-refuse thermal-mechanical lattice search
Organizations: Department of Mechanical Engineering, Santa Clara University, Santa Clara, CA 95053, USA. · Santa Clara University, Santa Clara, CA 95053, USA.
Abstract
Early thermal-mechanical lattice requirements are knowledge-intensive and often jointly unsatisfiable: an engineer asks for a cell that is light, stiff, laterally conducting and cheap, and no cell in the library satisfies it. A design system should say so, and say which requirement to loosen and by how much, rather than return the nearest row. A generative model can return a candidate even when the library holds none. This work applies established conflict diagnosis to a catalogue of homogenised properties. Search over 1,397 homogenised unit cells and 19 base materials (26,543 combinations) returns a catalogue row that a second solver can rebuild, or, for an empty feasible set of at most eight constraints, inclusion-minimal unsatisfiable subsets (MUS) and the slack of a repair, not a neighbour. One registry declaration generates the prompt and the evaluator, so undeclared parsed keys cannot reach search. On a frozen suite of 64 typed queries, retrieve-or-refuse matches min-repair on every feasible query (48/48) and refuses every empty one (16/16) with MUS and slack. Constraint-ignoring nearest-neighbour and penalty search violate stated cost or density limits. On 216 empty queries, repairs printed at three significant figures and rounded outward stay feasible in every case (216/216). When density and cost must be kept, a list of minimum-cardinality repairs keeps them on 209 of 211 queries; a protection-first repair keeps them on all 211, the same as full diagnosis. A 308-request parse benchmark is a template-text check, not unconstrained engineer prose.
Figures & tables
| System | Knowledge | Mode | Refuse | Headline evidence |
|---|---|---|---|---|
| Kartashov & Vlassis [ 4 ] | commands | generate | no | 2D cases |
| TrussGPT [ 5 ] | mech. targets | generate | no | experiment |
| Khanghah et al. [ 7 ] | graph tokens a | generate | no | reconstruction |
| MetaGen [ 6 ] | DSL + database | generate | no | case-study re-sim. |
| MetaSymbO [ 34 ] | language + latent | retrieve+evolve | no | validity / novelty |
| AutoMS [ 35 ] | NL + FEA loop | evolve | no | 17 cross-physics |
| Key | Kind | Unit | Provenance | Operators |
|---|---|---|---|---|
| rho | geometry | — | solved (isovalue bisection) | |
| k_aniso | geometry | — | solved ( , smaller is more directional) | |
| D_11 | geometry | — | solved ( , complete periodic pore) | |
| symmetry | geometry | — | solved (point group of ) | |
| cost_per_kg | material | USD/kg | handbook | |
| printable | material | — | handbook |
| Field | Role |
|---|---|
| weighted objectives | |
| constraint atoms | |
| material filter | |
| UNDERSTOOD AS | compiled , printed before retrieval |
| CANNOT EXPRESS | schema cannot name the ask |
| DISCARDED | undeclared or vacuous keys |
| Factor | In this catalogue | Solved? |
|---|---|---|
| Solid phase | 19 handbook metals/ceramics as , | no |
| Void phase | empty pore, | no |
| Volume fraction | by isovalue bisection | yes |
| Porosity layout | family, mode, , isovalue; voxel FE | yes |
| Solid | |
|---|---|
| copper | to |
| aluminium 6061 | to |
| AlSi10Mg | to |
| stainless 316L | to |
| Ti–6Al–4V | to |
| Target | Failure rate |
|---|---|
| – | |
| – | |
| above | none |
| Scheme | Fit to this geometry |
|---|---|
| Voxel FE (used) | One routine, both physics; deleting void elements is the zero-contrast treatment. |
| FFT [ 60 ] | Slow at infinite contrast, which is the regime here. |
| Mori–Tanaka [ 61 ] | Dilute ellipsoids; TPMS networks are percolating and not dilute. |
| Selection regret | at | |
|---|---|---|
| Top-three set | unchanged | unchanged |
| Max rank shift | — | of |
| value drift | ||
| value drift | ||
| drift |
| Axis | Count |
|---|---|
| Families modes target | |
| Target interval | |
| Enumerated cells | |
| Usable rows | ( ) |
| Metals / product | / |
| Cell size | Median | Fraction mm | Fraction mm |
|---|---|---|---|
| mm | mm | ||
| mm | — | — | none below mm |
| backend | independent | worst rel. err. | all within | |
|---|---|---|---|---|
| 60 | GPU, matrix-free | yes |
| Slice | Residual |
|---|---|
| Median / / | / / |
| Median at / | / |
| Worst at / | / |
| Median at , , | , , |
| Cells with | , all at |
| cell | voxel | scikit-fem hex | hex vs voxel | |
|---|---|---|---|---|
| gyroid network, | ||||
| Schwarz P sheet, | ||||
| IWP network, | ||||
| gyroid network, | ||||
| diamond network, | ||||
| diamond network, |
| cell | our | scikit-fem | worst component |
|---|---|---|---|
| gyroid network, | |||
| Schwarz P sheet, | |||
| IWP network, | |||
| diamond network, |
| Flash-Lite | Flash | Keyword table | TF-IDF 1-NN | |
|---|---|---|---|---|
| Overall | — | |||
| Literal | — | — | ||
| Paraphrased |
| count | rate | |
|---|---|---|
| First repair executable at nearest-even 3 s.f. | ||
| First repair executable, outward 3 s.f. (same queries) | ||
| Best-objective repair executable at nearest-even 3 s.f. | ||
| Best-objective repair executable, outward 3 s.f. | ||
| Disagree on dropped set | ||
| of which minimum cardinality one |
| count | rate | |
|---|---|---|
| Eligible queries | ||
| First repair (protection unused) preserves protected | ||
| Smallest-first list with protection | ||
| Protection-first repair (no MUS) | ||
| Full diagnosis (all inclusion-minimal MCS) | ||
| Smallest-first list fails; others succeed |
| Brief | Retrieve-or-refuse | NN / min-repair |
|---|---|---|
| Heat spreader , , , cost | Al 6061 diamond sheet, ( ) | NN: silver (violates cost). Min-repair: same as retrieve |
| Cheap conductor , cost | Al 6061 split-P, , USD/kg ( ) | NN: silver, USD/kg (violates cost). Min-repair: same as retrieve |
| Stiff and light , , cost | AlSi10Mg Schwarz P sheet, ( ) | NN: SiC (violates cost). Min-repair: same as retrieve |
| Light and stiff , | refuse; MUS ; slacks / GPa | NN: W Schwarz P, , (violates both). Min-repair: W diamond, , (keeps ) |
| Slice | refuse | exact | set-F1 | |
|---|---|---|---|---|
| All | 80 | 56 | ||
| Single-constraint boundary | 56 | 32 | ||
| Jointly infeasible pairs | 24 | 24 |
| Query | LOO | MUS | Pair |
|---|---|---|---|
| , , | extra not in MUS | ||
| , , | , | two pairwise conflicts | |
| , , | , , |
Appendix figures & tables2 assets
Supplementary material from the paper’s appendix.
Appendix
| Key | Kind | Unit | Provenance | Operators |
|---|---|---|---|---|
| rho | geometry | — | solved (isovalue bisection) | |
| porosity | geometry | — | solved ( ) | |
| k_aniso | geometry | — | solved ( , smaller is more directional) | |
| E_aniso | geometry | — | solved ( ) | |
| D_11 | geometry | — | solved ( , complete periodic pore) | |
| D_33 | geometry | — | solved ( , complete periodic pore) |
| Query id | Feas. | R | NN | Pen | MR | LD |
|---|---|---|---|---|---|---|
| s_rho_<=_0.12 | Y | Y | Y | Y | Y | Y |
| s_rho_<=_0.15 | Y | Y | Y | Y | Y | Y |
| s_rho_<=_0.18 | Y | Y | Y | Y | Y | Y |
| s_rho_<=_0.2 | Y | Y | Y | Y | Y | Y |
| s_rho_<=_0.25 | Y | Y | Y | Y | Y | Y |
Constraint Satisfaction
Constraint satisfaction studies how to find or optimize assignments that obey interacting rules across discrete and structured problems.
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