We call it swiss cheesing. Often it goes on the scale and gets the hole saw treatment until it's light enough. Nothing scientific.
As the students design, cam, and shop skills have improved we have done more milled triangles into our plates. This saved half the weight of our side plates. Can't say they were engineered but rather guess-gineered.
The isogrid looks attractive due to considerable weight savings but it does really drive up the material cost and machine time. If your milling away 90% of your material you better have deep pockets. A lot of isogrids and orthogrids appear to be on lightweight pressure vessels, like air and space craft. Is this because they work well in tension? I wonder how well this transfers to arms and such used in FRC. It would be neat to run some through FEA and see what it does.
This is a good read that I'm planning to use this season when we discuss grid lightening. Pre-season I think we'll make up some sample parts and see how they hold up. It will also give us an idea of how long the process may really take.
http://www.iccm-central.org/Proceedi...ers/pap357.pdf