Octet Truss Memory, Time and Dollar Costs

Cost for 3D Octet Truss Arrays

	i	j	k	time (s)	stl (bytes)	WSF ($)
1	1	1	1	1.47	73384
2	2	2	2	28.74	435384	2.61
3	3	3	3	173.32	1342184	4.99
4	4	4	4	873.20	3052984	9.46
5	5	5	5	2952.67	5826984	16.69
6	6	6	6	6694.16	9923484	27.32

This is a follow-up to the previous post on using the octet truss for topology optimization. The memory cost of performing the union of all the truss members in BRLCAD to generate stl files for printing was too large for the ToPy dogleg example so I generated a set of stl files for a range of arrays of octet truss unit cells. Then I uploaded them to shapeways to see how much they would cost to print in the white-strong-flexible nylon material. The table shows how long the python script took to execute, the size of the resulting stl file, and the cost to print the part on Shapeways in the white-strong-flexible material.


The size of the file and the cost to print the part scales linearly with the number of unit cells, however the time to perform the union shows quadratic scaling. This quickly becomes intractable for moderately sized arrays of cells.

Now I'm in need of a scalable algorithm to do fast boolean operations for constructive solid geometry.

Update: I had to add a frame around the bounding box of the parts to make them a bit more robust for cleaning and handling at Shapeways.

"it will break during unpacking/cleaning like this"

Update II: Here's the 6x6x6 part in Shapeway's white-strong-flexible: