Do the isolated feasible pockets of the 2 mm laser-cut bracket survive mesh refinement?

What it found

A small mesh-refinement scan (stylised, preliminary). The isolated feasible web widths below 15 mm that appear at 2.5 mm element size vanish at 2.0 and 1.5 mm, and the smallest feasible width moves up (14.4 to 15.6 mm at fillet radius 14 mm). Mesh convergence was not reached, and a stress peak at a corner is itself mesh-sensitive, so the least-mass design on the search mesh is optimistic.

Paper, code and results

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

More in Simulation-first design

• Is the narrow 2 mm laser-cut bracket region a mesh artefact?The narrow 2 mm laser-cut bracket region is a mesh effect: all 39 designs feasible at h = 2.5 mm fail the stress limit at h ≤ 1.5 mm (peak 1.09–1.27× higher, still rising at 0.75 mm); stylised, negative for the search mesh.
• Does a patch-averaged stress make the 2 mm laser-cut bracket region mesh-independent?A 3 mm patch-averaged stress converges with the mesh (≤2.2% change from h = 1.0 to 0.75 mm) where the centroid peak does not, and all 39 gauge-2 designs stay feasible; stylised, preliminary.
• Does the peak stress at the fillet tangent point of the L-bracket converge under graded mesh refinement?Does the L-bracket's peak stress at the fillet tangent point converge under graded mesh refinement? Yes for four designs: it flattens at 1.09–1.14× its 1.5 mm value (0.0–1.1% change over the last 4× refinement down to 0.025 mm), so the 2 mm region's mesh dependence is a resolution effect; the 16/15/2 design is marginally over 100 MPa when converged; stylised 2D, no reference solution.
• Is the least-mass laser-cut bracket the same on coarse and fine meshes under a patch-averaged stress rule?Under a 3 mm patch-averaged stress rule the least-mass laser-cut bracket is the same on a 2.5 mm and a 1.0 mm mesh (gauge 2: 32.31 vs 32.33 g), while the centroid-peak rule leaves no feasible gauge-2 design on the fine mesh; the patch value hardly sees the fillet radius; stylised, preliminary.
• Do cheap beam and 2D models rank candidate cantilever designs like 3D finite elements?Do cheap beam and 2D models rank cantilever designs like 3D finite elements? Yes on 3 seeds of 80 designs: Kendall τ 0.987–0.996 and the 3D-best design always ranked first, even though single-design merit is off by up to 14%; stubby sections agree least; stylised, one load case.
• Can a parametric L-bracket be sized by finite elements for minimum mass and come out printable?Parametric L-bracket sized by 2D finite elements (scikit-fem) for minimum mass under a stress limit: differential evolution 19.6 g vs random 25.6 g vs grid 31.4 g at equal budget, exported as STL with a printability check. Assumed material inputs. 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.