[TheSpiceIsLife]

The gold standard around these parts is purported to be Tekla Structures. No affiliation, just a structural steel guru who’s happy to work with the fabrication drawings it spits out.

I can spot Autodesk fabrication draws a mile away. Either the steel detailers don’t know how to configure it properly, it, as I suspect, it’s a steaming pile of dumpster fires.

I used Autocad for 2D CAD quite a bit, and I don’t see the appeal. There are competing products at a fraction of the cost.

[poseva]

Indeed. Autodesk Advance Steel generated fabrication drawings need a lot of effort to get it right but AS was ahead of Tekla in regard with connection design and modeling/detailing super strange parts/structures.

As for the prices...in 2014, 2 Advance Steel licences were something like 12000 euros and one Tekla license was about 18000 euros.

[ramshanker]

Yes. Totally agree on TEKLA Structure. Their Concrete detailing also improved substantially in past few years.

[namibj]

Is there anything a non-professional can use for the following four usecases (separate software is ok):

1) Reinforced concrete structure design, with support for non-trivial surfaces (e.g. splines/Bezier curves/surfaces).

2) Non-finely-meshed (in comparison to local volume thickness) truss structures, ideally not just classic steel beams + welded/riveted joints,

3) but also aluminium (considering fatigue from non-stationary loads and optimizing for the lifespan/weight/cost pareto frontier (cost would be just a simplistic metric)).

4) The holy grail, a 3d-printed core (technically a large-pore-size, low-density, open-pore foam) that is then covered by fibers via a robot that passes the spool around the core/preform (filament winding). After hardening the matrix that bonds the fibers together, the 3d-printed core could optionally be removed by melting and/or solvent washing. This kind of structure is potentially extremely stiff due to combining the truss structure with cylindrical beams and a lightweight fiber-reinforced polymer material.

The issue is just the insane non-triviality in designing such a structure, because there are restrictions to holes and fiber angle shifts due to the winding process, where the fiber bundle has to be accurately woven around the mesh in the designed way. This, combined with the directionality of the fibers makes it necessary to consider much more than normal 3d-printable topology optimization[0].

A concrete-ish example would be a multi-monitor + keyboard/mouse support structure to enable a low-fatigue position where the user leans back about 30~60 degrees to allow the neck to be supported and the user's practical FOV (w.r.t. feasibly eye/head movement) is covered by screen area and the arms can rest on supports. The constraint that makes a traditional steel truss undesirable would be to have it mobile (thus lightweight), yet stiff enough to handle ~5 m/s² without impairing usability. A practical case would be to overlay travel with getting work done, by mounting this in the back of a van (including straps/seatbelts as required) and being driven.

A different practical example could be amateur airplane design, e.g. devising an autonomous solar glider, where some stiffness is required to not break the solar cells laminated into the wing surface (thinned wafers are lighter and can conform to the wing's curvature, but will then dislike the wing flexing along the span), but weight is extremely important. Mounting the heavy things (motors, some backup batteries, potential payload) and handling control surface actuation forces won't easily work with a simple fiber-reinforced hollow wing, as a lack of dedicated mounting points (with their own fibers distributing the forces into the outer structural surface) would require a far heavier construction.

It's also difficult to consider aerodynamic forces when computing pre-distortion of the unloaded structure, so that design loads make it take on the desired shape, if there are also ad-hoc mounting brackets glued to the inside surface (which would be necessary if they're not designed into the primary structure).

Sorry for the slightly-OT examples.

[0]: Project video "on using the free version of Fusion360 for shelf brackets printed in PLA on a Prusa i3 MK3": https://www.youtube.com/watch?v=3smr5CEdksc - Thomas Sanladerer: Making STRONG shelves with Topology Optimization

[TheSpiceIsLife]

Hi there.

I’m a metal fabricator by trade and work closely with engineers and steel detailers.

You ask for a non-professional solution to four professional grade problems.

So I doubt your gong to get a satisfactory answer.

[namibj]

Well, one doesn't need to be professional to the extend where one can argue Tekla Structures to be worth the cost, if the goal is to design structures for hobby/DIY work.

Depending on the purpose, structural failure might be sufficiently low-risk to not need more than a cursory glance by an engineer to check whether the concept is sufficiently-sane and the stresses the software calculated are no reason to worry.

People today build these structures without software-assisted structural analysis. Or anything, really, beyond rough numbers.

I hope there'd be something that be good enough to not fly blind when working on hobby projects that would benefit massively from clever structural design. Finding someone qualified to look over the finished design is often reasonable, but paying them to do clerical work (e.g. re-drawing your blueprint in their CAD, just to get the computer to calculate stresses), would be too expensive.

I just see that these tools all have license fees where any non-full-time usage is directly prohibitive.

Even if a good tool has e.g. 500$ + 20% royalties (of the sale price), that'd be far better than what I see out there from my searching.

[TheSpiceIsLife]

I see and understand your point and agree to some extent.

Not real sure what to do there?

I'd maybe consider doing a course at my local Tafe ( https://en.wikipedia.org/wiki/Technical_and_further_educatio... ) and do a design course and get friendly with the people who work there and run the workshop part of the campus so they might let you continue to use the facilities are you've finished.

Not sure if you have anything like that around your parts.

[Woberto]

Sounds like you might want to use something like finite element software, which is essentially what other programs do. FEniCS is an example of an open source library that could maybe help. People usually use something like ls-dyna or Abaqus

[namibj]

Yes, of course. But I'm specifically interested in the design side, because the analysis side is already handled by open and/or free software, due to it being so close to what a small university research group might just publish or adapt for unconventional FEM analysis.

Design software is much less easy to find, though.

[Woberto]

Ah, sorry. Have you tried rhino 3d? There are some nice additions to it like grasshopper