topic Re: Simulation with Scan file in Fusion Design, Validate & Document Forum

Simulation with Scan file

davidhuels89 — Sun, 07 Aug 2022 21:22:07 GMT

Hi there, I have a watertight 3D scan file (STL) and want to use it directly for simulation (FEM analysis). I assumed that this is possible without reverse engineer it to a CAD body. So for, I was not successful. Any suggestions?

Re: Simulation with Scan file

jhackney1972 — Mon, 08 Aug 2022 00:16:47 GMT

The mesh body must be converted into a Solid body before it can be used in the Simulation environment. This is done in the Design Environment using the Mesh toolbar. Screencast is attached.

Re: Simulation with Scan file

TrippyLighting — Mon, 08 Aug 2022 00:33:52 GMT

Have you been successful in getting useful simulation results from such a highly faceted solid body ?

Re: Simulation with Scan file

davidhuels89 — Mon, 08 Aug 2022 08:39:15 GMT

Hi John, wow what a great support - thank you so much!! 🙂

I will try it today in the afternoon and give you feedback then (time zone Germany)

Re: Simulation with Scan file

davidhuels89 — Mon, 08 Aug 2022 08:43:53 GMT

Hi @TrippyLighting Peter,

I'm just starting with FEM Analysis. I want to do fatigue analysis for weld construction on welds which a critical.

I read in the paper below, that there should be no difference to do FEM analysis on a modeled CAD or directly in the scan data. Of course, this would speed up the process a lot. I'm not sure which software the study used for the FEM analysis.

(PDF) The Importance of 3D Scanned Mesh Processing in FEM Simulation Results (researchgate.net)

Re: Simulation with Scan file

TrippyLighting — Mon, 08 Aug 2022 15:25:31 GMT

I don't believe this is a project for a beginner in FEA for a number of reasons.

CAD software works with BRep geometry. When an FEA is initiated that BRep geometry goes through a meshing stage. This is a volumetric mesh, most often comprised of tetrahedrons. It is NOT the often encountered .stl or .obj surface mesh.

So in order to get this to work with Fusion 360 you need a BRep, not a surface mesh. When you import a surface mesh into Fusion 360 and convert it into a highly faceted BRep. The meshing algorithms work best on simple geometry, which is also the reason Fusion 360 and other CAD software allow to simplify even native CAD geometry in order to help the meshing process.

It is very possible that the algorithms that do the meshing stage badly choke on that highly detailed faceted nature. Even if they succeed you'd be wise to inspect the generated volumetric mesh to determine whether it is suitable for FEA analysis. That requires a good bit of experience!

I cannot find it at the moment, but remember a Autodesk University lecture on FEA on welds. The recommendation was NOT to do it due to the large number of variables in welded structures that can render simulation results invalid or unusable.

Also, the Paper you listed did NOT state there is no difference. It states:

It can be confirmed therefore that, the use of a 3D scanned model instead of the original CAD is not a cause of significant error if mesh geometry has a minimum quality.

That is a heck of a different statement, and also you need to take in consideration what FEA they conducted and on what materials. Rubber and Steel obviously have very, very different properties.

Re: Simulation with Scan file

davidhuels89 — Thu, 11 Aug 2022 15:14:52 GMT

As @TrippyLighting assumed, after the conversion the BWrap Body has too many facets. See below my new solution I found. I will post it within the next hours.

Re: Simulation with Scan file

TrippyLighting — Thu, 11 Aug 2022 20:20:45 GMT

@davidhuels89 wrote:

As @TrippyLighting assumed, after the conversion the ~~BWra~~p Body has too many facets. See below my new solution I found. I will post it within the next hours.

BRep