Calculating Serrurier Truss Deformation

Calculating Serrurier Truss Deformation

If you don't know what this is, see here. I'm thinking of seeing if I can reduce the weight of Big Bertha 2.0 by replacing the current combination of aluminum tubes, turnbuckles, and guy wires, with a single Serrurier Truss design. Moonlite Accessories sells components; I need to figure out how to compute the deformation of a Serrurirer Truss design, to see if I can replace the current scheme with something that would be just as stiff, but lighter.

My intutive sense (which is often wrong), is that the deformation of any single tube will be the same as a tube parallel to the optical axis, but with cos and sin included as well! In addition, the top and bottom tube assemblies necessarily add some stiffness, so the total deformation of a six tube truss will be a maximum of 1/6th of the deformation of a single tube. (And in practice, of course, a bit less.) A book called The Design of Welded Structures has been recommended, but if I can find something online (or an expert in my readership--very likely!), all the better.

The current scheme where I have a single aluminum channel that runs the length of the telescope can be replaced with a single piece of channel that runs from the lower section (where more than 3/4 of the weight is located) to the mounting plate. This, by itself, will knock at least six pounds off the total weight. If replacing the current square tubes, the guy wires, and the turnbuckles, managed to knock another two or three pounds off the total weight, it would be worth it. (That would get Big Bertha 2.0 down to about 48 pounds.)

The other advantage is that I could disassemble Big Bertha 2.0 easily and quickly for vehicle transport, and it would simply putting on the mount, because I could put the lower assembly onto the mount as a somewhat lighter, and considerably less unwieldy structure, then put the tubes in place, and mount the upper cage on the tubes.