Does relaxing the 1.2 mm minimum-wall rule open thinner sheet gauges for the laser-cut bracket, or is the buckling floor what binds?

What it found

A small optimiser study (stylised, preliminary; the buckling factor is an unvalidated ideal-bar closed form). Relaxing the minimum wall from 1.2 to 1.0 or 0.8 mm changes nothing at 1.5 mm (31.0 g in every cell) and does not by itself open 1.0 mm sheet: with a buckling-factor floor of 3 no design exists at 0.8 or 1.0 mm (the widest allowed web reaches a factor of only 1.5 at 1.0 mm). With a floor of 1 and a minimum wall of 1.0 mm or less, a 1.0 mm design appears at 24.8 g (w = 22.7 mm, factor 1.33, 2 of 3 seeds), 20% under the 1.5 mm optimum, but a factor of 1.33 from an ideal-bar formula is no margin. Simulated results only.

Paper, code and results

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

More in Simulation-first design

• Does the lightest 1.5 mm bracket design clear buckling in a converged 3D eigenbuckling model?A through-thickness-converged 3D eigenbuckling model agrees with the closed-form buckling factor of the lightest 1.5 mm bracket design to under 1% (3.49 vs 3.47, so it clears the floor of 3); the horizontal-arm formula is about 18% conservative; one design, ideal bar, preliminary.
• What changes when the w/b ≤ 8 slenderness ceiling of the laser-cut bracket is replaced by a buckling-factor floor?Replacing the w/b ≤ 8 ceiling with a closed-form buckling-factor floor makes the 1.5 mm laser-cut gauge feasible (31.0 g, about 13% lighter than the best 2 mm design) and changes nothing at 2 and 3 mm; at 1 mm the minimum-wall rule, not buckling, blocks every design; stylised, unvalidated factor, preliminary.
• Does lateral-torsional buckling justify the w/b ≤ 8 slenderness rule of the 2 mm laser-cut bracket?A closed-form lateral-torsional buckling check of the laser-cut bracket arms (stylised, unvalidated by FE): at 2 mm gauge the governing safety factor is 6.9–9.0 for w = 16–20 mm, so the widths of simdesign-widerweb are not buckling-limited, and the factor rises with w, opposite to the w/b ≤ 8 rule; at 1 mm the old rule admits designs below 1.
• Do the closed-form buckling factors of the laser-cut bracket arms agree with a 3D eigenbuckling model?A 3D scikit-fem eigenbuckling check of the bracket-arm closed forms (stylised, mesh not converged): within about 1% for the governing vertical arm, conservative by 6–29% for the horizontal arm at the 2 mm gauge.
• Does refining the mesh of the 3D eigenbuckling check change how the closed-form bracket-arm buckling factors compare?Mesh refinement of the 3D eigenbuckling check of the bracket arms (stylised): refining length, width and thickness lowers every FE/closed-form ratio by 0.9–1.3 points, so the governing vertical arm agrees with the closed form to within 1% (ratio 0.99–1.00 at the finest mesh).
• At what bar slenderness does the 3D eigenbuckling model agree with the slender-beam closed form?How the 3D eigenbuckling model compares with the slender-beam closed form as a bar gets longer (stylised): the finite-element load is 14.5%, 7.4%, 3.8% and 2.1% above it at l/w = 3, 6, 12, 24.

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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.