Simulating Tubular Truss structures

[mterke]

To all;

The 'CADWhisperer' suggested I post on this board of the forum.

I have been using the simulation tool for the last 10 months now, and in particular the static stress tool. All of the structures I have simulated have included tubes of various lengths and wall 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 the 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 calculations.

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.

Any help would be greatly appreciated.

[John_Holtz · Accepted solution]

Hi @mterke 

Ironically, computers are not very good with numbers. 😁 Even when a model is theoretically perfect so that all of the faces match up and the body becomes a solid, internally the edges can be separated (usually at the 8th decimal place, so the edges are very close to being the same but not exactly the same).

I do not know about Fusion, but often there is a tolerance used when meshing to help avoid such mismatches. The tolerance is usually related to the mesh size, the overall model size, and/or the position of the model in 3D space. So the questions that come to mind are as follows:

• The error message usually flags exactly where the problem occurs. Zoom into that area, slice the model if necessary to look inside, and look for any sliver surfaces or distorted edges or faces. Clean up the area if you see any, such as adding a chamfer or round. 
• Does the model mesh with a larger mesh size? With a smaller mesh size?
• Is the model fairly centered around the origin? If you were to put it in a box, would the center of the box be relatively close to the origin? (If it is off by 100 units, that is no problem. If it is off by one million units, that could be a problem.) If the model is off, does moving the model help?

If you still have problems, I suggest that you export the model (File > Export) and attach the .f3d file to the forum.