Does a mesh-aware stress margin change what manufacturing rules cost a sized bracket?
research/simdesign-meshmargin
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).
What it found
The process-rule search of simdesign-dfm is repeated with a coarse mesh, a coarse mesh with the stress limit divided by 1.3, and a finer mesh, and every design is re-solved on a finer check mesh. The ordering of the mass prices survives: casting about 1.4, CNC routing about 1.23, FDM 1.0 by construction. The laser-cutting price does not (1.01 to 1.22 across settings, with only two seeds). A margin of 1.3 leaves the designs at 0.88 to 1.02 of the limit on the check mesh, at a 17at a 20–35% mass costndash;35% mass cost. Stylised: the peak stress is not converged even on the check mesh, rule values are assumed, and nothing was made.
A figure from its own output
Paper, code and results
More in Simulation-first design
- 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). - Where does the peak-stress price scatter of laser-cutting rules come from?Follow-up to
simdesign-filletfloor: the peak-stress price scatter of laser-cutting rules (sd 0.063) sits in the 2 mm gauge sub-search, not the fillet floor; a four-times search budget cuts it to 0.025 but not monotonically, so several nearby optima are plausible but not shown (five seeds, stylised). - Does a patch-averaged stress give a mesh-converged stress concentration for a bolt hole?Patch-averaged stress for a bolt hole in a tension strip: nearly settled under mesh refinement already, matches Kirsch's disc averages, needs its own limit (stylised).
- How far below the exact stress concentration does a finite-element peak stress sit, and how fast does it close?Checks the finite-element peak stress at a circular hole against Kirsch's exact 3× concentration: the element-centroid peak sits 27% (coarse) to 1.1% (fine) below it and closes only at first order, while hole-edge vertex values are within 1% (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.