Alpaca4d

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Find a structure with topology optimisation ​

Start from a block of material, supported and loaded, and let Alpaca4d keep only the material the loads need: the stiffest structure for the share of the volume you allow.

A bridge found by Topology Optimisation in a block of bricks: an arch rising into the deck

You need ​

Steps ​

  1. Give an ElementId to anything that must stay solid: a deck, a slab, the material round a support or a load.
  2. Place a Topology Optimisation and wire the assembled model into AlpacaModel; name what must stay in Keep.
  3. Set VolumeFraction, the share of the volume to keep: 0.3 by default. The solids in Keep come on top.
  4. Set Run to true. The run goes on its own thread, so Rhino stays free, and Surface follows it about once a second.
  5. When it stops, wire AlpacaModel, the design as a model of its own, into Run Analysis, and read it as any analysed model.

Check ​

  • Converged is true: the run ended because the densities stopped moving. If it stopped at Iterations, raise them, and it goes on from where it stopped.
  • Compliance, the work of the loads, falls as the run goes on: the lower, the stiffer.
  • Step, with a slider, shows the design of every iteration, to watch the run again.

Good to know ​

  • Set Run to false to pause; true goes on from there. Changing the model, Keep, VolumeFraction or a setting starts again from the beginning.
  • FilterRadius, in the settings, is about the thinnest member the result can have.
  • Beams, trusses, shells and links in the model are analysed with the solids but take no part, and the component warns that they are there.
  • BESO Topology carves the block down, every element solid or void; Multi-Material Topology finds where each of several materials goes.

See also ​