FEA analysis on an OBJ file. Having issues with meshing

[hariskhalil]

Hello,

I have an OBJ file of a model generated from a tool path on which I want to do an FEA analysis. 

When imported to Fusion 360, I triangulate the mesh, and convert to BRep, where my facets come below 10000.

I open the simulation workshop, the model gets imported, but when I try to Mesh, I get no error warnings and the progress bar just disappears.

What can I do regarding the mesh to simulate .? 

I have attached the f3d file.

Thank you!

[John_Holtz]

Hi @hariskhalil 

It looks to me that you do not have a solid model. It looks like it is only a surface. When I create a "Inspect > Section Analysis" in the Design environment, it does not show a cross section. It is as if the model is made from paper: it has a surface but no thickness.

The Simulation environment can only analyze solid models. It cannot analyze a surface model (which would be analyzed using shell elements).

I do not know the modeling aspect of Fusion, but there should be some method of importing your object and converting it to a solid instead of a surface. Do you have any other file format that can be used for importing such as a STEP format?

[hariskhalil]

Hi John,

I have managed to convert my model to solid by going through a very long and painful methods. I realized the mesh itself was not very good and managed to remesh on fusion using "close mesh" option and than reduced the face count and performed my analysis. 

However my results arent very accurate due loss of details when reducing the facet count.

Is there any way to work on high facets counts (like in millions) and convert to solid while preserving all the details of the model? Would that require me to purchase a package in AutoDesk. ? I would love to know more about it.

Thank you!

[John_Holtz]

Hi @hariskhalil 

I think the first step is to figure out what you are trying to analyze and make the model to suit the analysis. Perhaps you have done that already, but the model provided does not look like it is suitable for an analysis. Here's a simplified sketch of what I see in your Body1.f3d file:

1.  Item 1 is what I see in the actual model. Many of the diamonds are interfering with each other. Should they "magically" pass through each other?
2. Should the model be like this? If so, how are the diamonds held together? Is it like a hinge and each diamond can rotate at the joint (as shown in the detail)? That is, they are not welded or glued or "melted" together. It is a "living hinge" and one diamond can flex/rotate relative to the adjacent diamond.
3. Should the model be like this? The parts are continuous and welded or glued together (either as shown where the common faces can transmit the equivalent of a moment, or in the detail where the diamonds are all "melted" together).

The next question is how do one row of diamonds connect to the row underneath. In your model, most are just touching at a point where they touch. This will not transfer a load between rows in the analysis (or certainly not very accurately). 

The diamond-shape bars cross at an angle. Therefore, the contact between 2 diamonds is a single point.

Next is the question about creating the model. If you cannot export the model as a STEP (.step or .stp), ACIS (.sat) or IGES (.iges or .igs), then you should create the model in Fusion.

If you have any other questions about the modeling, whether importing your model or creating it from scratch, I suggest that you create a new post. The text "FEA analysis" in the title of this post will limit the responses from the modeling experts that you want to participate in the conversation. In other words, the real problem is creating the model properly. The fact that you want to use it for an analysis is not important (at least not yet, not until you have the proper model and have question specific to the simulation).