Do the mass-weighting machine-choice flips of simdesign-coverweight survive across seeds?

What it found

Follow-up to simdesign-coverweight, whose machine-choice flips between count and mass weighting came from one seed. Over 20 fresh seeds of 20 000 sampled brackets and three assumed machines, family log picks the laser cutter by count but the casting setup (or, in 2 seeds at 800, the CNC router) by mass in 20 of 20 seeds at budgets 600 to 800 (95% Wilson interval 0.84 to 1.00; about 2.1 points of mass-weighted coverage given up), family large flips only at budget 800 (20 of 20), and small never flips. The log flips at 1100 and 1400 split 10 of 20 but lose at most 0.26 points, a near-tie. The intervals cover sampling noise only; rules, prices and the volume mass proxy are assumptions. Stylised; simulated only.

A figure from its own output

Paper, code and results

• README and method
• Experiments and results
• Code
• Tests

More in Simulation-first design

• How wide are the budget bands where mass weighting changes the machine choice when prices are uncertain?How wide are the budget bands where mass weighting changes the machine choice when prices are uncertain? With ±20% independent price noise the log flip band widens from budgets 600–800 to 500–1000 but softens at its edges (about one half), and large's single nominal flip at 800 shows up in only 44% of price draws. Stylised, assumed rules and prices, simulated only.
• Which share of a bracket family can each shop process make, and which machine should a shop add next?Share of a sampled bracket family each shop process can make under the simdesign-dfm rules: geometry alone adds nothing beyond FDM (negative), with a tip-load requirement the processes separate (FDM alone 30%, +casting +laser 41%) and the best next machine depends on budget and part size, where greedy sometimes loses 1–2 points to exhaustive search (stylised, assumed rules).
• Does a mesh-aware stress margin change what manufacturing rules cost a sized bracket?Re-runs simdesign-dfm with a stress knock-down and a finer search mesh, checking designs at h = 0.7 mm: the price ordering (casting ~1.4, CNC ~1.23, FDM 1.0) survives the mesh, the laser-cutting price does not (1.01–1.22, noisy), and a 1.3 margin leaves designs at 0.88–1.02 of the limit (stylised, assumed rule values).
• Does a patch-averaged stress converge under mesh refinement where the peak element stress does not?Compares peak and patch-averaged von Mises stress under mesh refinement on the L-bracket: the peak rises 18–41% from h = 2.5 to 0.55 mm while a 3 mm patch average moves 1–6%, but it reads only 0.45–0.69 of the peak so needs its own limit (stylised, assumed values).
• Does a patch-averaged stress change what manufacturing rules cost a sized bracket?Repeats the process-rule bracket search with a 3 mm patch-averaged stress instead of the peak: the ordering of mass prices (casting > CNC > laser ≈ FDM) holds, the laser price spread across seeds shrinks from 0.16 to under 0.005, and designs overshoot their limit by 2–12% on a fine mesh against 19–34% for the peak (stylised, assumed values, uncalibrated limit).
• Is the shrinking laser-cutting price scatter under the patch stress caused by the near-sharp fillet floor?Tests whether a near-sharp fillet floor explains the laser-cutting price scatter seen in simdesign-patchsearch: it does not (peak-stress designs already use 7.6–14.3 mm fillets, so floors of 0.2 and 1 mm give identical designs); the patch-stress price is steady (sd 0.006–0.011) at every floor, and the cause of the peak scatter is not identified (negative, five seeds, stylised).

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Produced with AI assistance (Claude). Results are from the code in this repository and are simulated or stylised unless the abstract says otherwise; nothing here implies affiliation with or endorsement by any lab, researcher or company cited. MIT licensed.