topic Re: Simulating Tubular Truss structures in Fusion Support Forum

Simulating Tubular Truss structures

mterke — Thu, 10 Dec 2020 03:28:38 GMT

I am attempting to do a static analysis on a tubular truss structure. Most of the elements are 1.25" by 0.049" wall thickness. Meshing this is very difficult and completely unpredictable where it will fail next. Messages like 'self intersecting' and 'small feature' are not helpful at all. In the current case there are 4 identical pieces of tubing and one has the meshing error 'small feature'. Equally, there are two identical (mirrored) faces, one of which has the same 'small feature' error.

Thus far I have gotten the structure to pass the meshing phase a few time, but I have no idea how nor why.

Most time Fusion gives the message that some elements are very thin. Sometimes it passes, sometimes it doesn't.

When coping tubular structures you are going to have thin walls.

Any suggestions?

Regards,
Mark

Re: Simulating Tubular Truss structures

TheCADWhisperer — Thu, 10 Dec 2020 11:50:42 GMT

@mterke wrote:
I am attempting to do a static analysis on a tubular truss structure.
Any suggestions?

Autodesk Inventor Professional- Frame Analysis uses beam elements.

Re: Simulating Tubular Truss structures

mterke — Thu, 10 Dec 2020 19:23:58 GMT

I'm not sure what you mean by that.

Re: Simulating Tubular Truss structures

TheCADWhisperer — Thu, 10 Dec 2020 19:34:44 GMT

Fusion 360 does not have Beam Analysis tools yet.

But Autodesk Inventor does. My suggestion was to check Inventor.

If you are a student - you can download Inventor for free.

Re: Simulating Tubular Truss structures

mterke — Thu, 10 Dec 2020 21:03:37 GMT

You'll have to bear with me because I still don't understand.

I have been using the simulation tool for the last 10 months now, in particular the static stress tool. All of the structures I have simulated have included tubes of various lengths and thicknesses. In almost all cases these tubes intersected each other. I modeled holes or copes in each case. Meshing those rarely failed. Running the solver worked reliably.

This time I am modelling an engine mount made up of tubes as well. The tubes are all carefully cut and coped in the model. A few times it passed the meshing stage and the solver had no problem solving the system. However, most of the time the meshing stage fails. It never even gets to point where I can run the solver.

The results I got from the few times things worked as expected, the results agreed well with my paper calculation.

Therefore; it seems that the solver is capable of solving this structure. It is the meshing step that fails. At the moment I'm looking at a "Meshing Error! Phase: Surface meshing. Description: Face interior" message.

Considering the few successful runs of this model, I do not understand the need to go to another program.

Thank you for your time.

Re: Simulating Tubular Truss structures

TheCADWhisperer — Thu, 10 Dec 2020 21:19:35 GMT

Ahh, it would not have occurred to me to attempt to run a tetrahedral mesh solver rather than beam elements solver on something like this.

You might get better Autodesk response on this >>over here<<.