Edison query on strut material (PLA vs PETG vs HF/CF) — fetched + interpreted

[Copilot]

Issue asked: what is the right strut material for our PETG/TPU multi-material FDM tensegrity (PLA vs. PETG vs. HF-reinforced or other), via an Edison Scientific query whose results we then interpret. This PR submits the query, blocks for the result, commits all artifacts, and writes up the recommendation.

Changes

• scripts/edison/submit_strut_material.py — LITERATURE_HIGH submission (blocking) scoped to our actual constraints (Bambu H2D, 0.4 mm nozzle, TPU 95A tendons, energy-absorption loading, ≥2 mm strut Ø). Compares PLA / PETG / CF-PLA / CF-PETG / continuous CF/Nylon / ABS / PC / PA-CF and disambiguates "HF-reinforced". Forwards EDISON_API_KEY → api_key= since edison-client only auto-reads EDISON_PLATFORM_API_KEY.
• edison-trajectories/strut-material-selection-5bb5e5d3-...{md,json,-references.md} — verbatim formatted_answer (47 KB, 38 cited refs w/ DOIs), full structured response, and extracted references section. Task 5bb5e5d3-b386-4ece-a894-9c87f0d67036, status success. Edison returned no separate file artifacts for this task; everything is in those three files.
• edison-trajectories/strut-material-selection-summary.md — interpretation, ranked recommendation table, interface-evidence table, and proposed references.bib additions.

Findings (TL;DR)

Rank	Material	Verdict
1	PLA (keep baseline)	Only rigid/TPU pair with peer-reviewed bond data: PLA–TPU 6.5–7.4 MPa tensile, ~24 MPa shear w/ mechanical interlocking (Lopes 2018, Zhang 2026, Ruwais 2025). Highest neat-polymer stiffness → ~2× Euler buckling vs. PETG; best fatigue + UV.
2	PETG (Phase-2, conditional)	+20 °C HDT, more ductile, but no peer-reviewed PETG–TPU bond number exists — must be experimentally validated before adoption.
3	CF-PETG	Phase-2 only if buckling dominates; hardened nozzle, ~2× cost, no CF/TPU bond data.
—	Continuous CF/Nylon	Out of scope: not H2D-compatible, can't co-print TPU.
—	"HF-reinforced" = hemp-fiber PLA	Not competitive: impact drops 69.8 → 42.9 J/m, porosity 5.8 → 17.9%.

Novelty bonus: no prior peer-reviewed work uses a PETG- (or fiber-reinforced-) strut + TPU-tendon tensegrity, so the proposed architecture is a publishable contribution as scoped. Action items for proposal.tex / references.bib are at the bottom of the summary file; this PR does not yet edit the proposal text.

[sgbaird-yolo]

@copilot where else in the repo do we need to update to reflect that we'll stick with using PLA? I'm not really seeing upsides to trying to use PETG.

[Copilot]

@copilot where else in the repo do we need to update to reflect that we'll stick with using PLA? I'm not really seeing upsides to trying to use PETG.

Good news — on this branch, all proposal-side artifacts already say PLA, so nothing here needs to change. Audit on copilot/research-strut-material-options @ 0e28415:

• README.md:16 — "PLA struts + TPU tension elements" ✅
• proposal.tex lines 64, 100, 133, 136–137 — PLA struts, PLA–TPU interface ✅
• sections/coverpage.tex:28 — "Using PLA for rigid…" ✅
• sections/budget.tex:40 — "PLA/TPU filament" ✅
• idetc-abstract.tex lines 42, 82, 120, 157 — PLA struts, PLA–TPU co-print ✅
• reviews/mock_reviews.md lines 98, 104 — PLA–TPU ✅
• references.bib — no material mentions, nothing to flip ✅
• Zero "PETG" occurrences anywhere on this branch.

Where PETG-as-strut does still appear (per stored notes) is on other branches that would need follow-up PRs:

1. Manuscript branch — manuscript-body.tex has ~3 PETG mentions in the strut context (from the mock-JMD review notes). Should be flipped to PLA + cite Lopes 2018 / Zhang 2026 / Ruwais 2025 for the PLA–TPU interface numbers.
2. Simulation branch — simulations/printable_design.py defines a PETG material card (E=2000 MPa, ρ=1270, σ_break=50) for the strut. Should swap the default strut material to PLA (E≈2.4 GPa, ρ≈1250, σ_break≈50 MPa, σ_c≈82 MPa) and keep PETG only as a Phase-2 comparison entry.
3. Joint-design branch — cad/joint-design/ SCAD files and the dovetail/anchor-bulb geometry were sized assuming PETG-strut + TPU-tendon; the geometry is material-agnostic (clearances are TPU-side), but the README/manifest copy should be updated to "PLA strut + TPU tendon" to match.

Happy to open the follow-up PR(s) against those branches if you want — just say the word and which one to start with.

[Copilot]

Pull request overview

This PR adds a reproducible Edison Scientific LITERATURE_HIGH query workflow and commits the resulting artifacts plus an interpreted recommendation for selecting strut material (PLA vs PETG vs fiber-reinforced options) for the multi-material FDM tensegrity project.

Changes:

• Added a blocking Edison submission script that writes the formatted answer, structured JSON, and a references markdown file.
• Committed the full Edison response artifacts for task 5bb5e5d3-b386-4ece-a894-9c87f0d67036.
• Added a human-readable summary with ranked recommendations and proposal action items.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
scripts/edison/submit_strut_material.py	Submits the Edison query, blocks for completion, and writes response artifacts to edison-trajectories/.
edison-trajectories/strut-material-selection-summary.md	Interprets Edison output into a ranked material recommendation and proposal action items.
edison-trajectories/strut-material-selection-5bb5e5d3-b386-4ece-a894-9c87f0d67036.md	Verbatim Edison formatted answer (question + answer + numbered references).
edison-trajectories/strut-material-selection-5bb5e5d3-b386-4ece-a894-9c87f0d67036.json	Structured Edison response payload persisted for reproducibility.
edison-trajectories/strut-material-selection-5bb5e5d3-b386-4ece-a894-9c87f0d67036-references.md	Extracted references list intended for easier citation/BibTeX ingestion.