How to mesh it?

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  • Last Post 11 July 2018
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Ulvi posted this 10 July 2018

So I have a geometry as attahced picture1. I used sweep meshing option and refined mesh at around perimeter and thickness as resulted as in Picture2. But when i slice the geometry I see the picture 3

Any clue how I can get elements shared inside the thickness correctly? I have assigned 5 elements to upper and lower boundary and 6 elements to sides but inside the geometry does not mesh properly.

 General model in Picture 4

 

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peteroznewman posted this 10 July 2018

You have to assign a Mesh Control Method = Sweep. That will result in a hex mesh on the inside as well as the outside.

Ulvi posted this 10 July 2018

I have already tried it alongside some other tecniques but could not achieve it. Just uploaded the model to original post. Appreciate if you could give a glance

peteroznewman posted this 11 July 2018

I opened your model, exported the geometry to a Parasolid file. |
When I tried to import the Parasolid into NX11, I got this error:

That is not a good sign...

I exploded the Part and used Unite to put it back together. That was able to export/import into NX11.

Ulvi posted this 11 July 2018

Why do you need to do that? I thought, some meshing tecniquesin WB would be sufficient to solve the problem?

I have attached .step file that I used to import SolidWorks model into Ansys

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peteroznewman posted this 11 July 2018

Import of Parasolids into NX11 was a way to check for geometry defects.

I recommend you use some Tetrahedral elements on this model around the joint, and have hex elements on the tubes.

One job I had five years ago was to find a design that could support a large load at the end of a long beam. In the image on top, the beam was initially horizontal. This design could not support the large load. The material model includes plasticity and you can see in the zoomed in view that there are tet elements in the joint, and hex elements on the tubes.

Three slice operations, put the parts into a multibody part, and you have a successful mesh in no time.

Rather than chamfers, this geometry used blends to represent the welds between the tubes.

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peteroznewman posted this 11 July 2018

I read your STEP file into SpaceClaim. I combined all the bodies back into a single body. On the Repair tab, clicked the Inexact Edges tool.

It found six, but could only repair four.  Two inexact edges remained. This may cause problems meshing.

Also, I can't remove this extra face.

Precise geometry is needed for easy meshing. Inexact edges are going to deliver poor quality meshes as I found in this trial below.

    

It might be worth building this geometry from scratch in SpaceClaim. I did a blend instead of a chamfer and used a sphere to slice out the joint.  The parasolid file for that is attached in the zip file.

Regards,

Peter

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Ulvi posted this 11 July 2018

Solution to the problem is to apply face mesh to cross section which is a easy solution for me.

 

Thanks for sharing your experience. My project is an academic research project and I have to bear to welding specification as per AWS. On the top of it, mesh convergence study becomes more representable with sweep mesh. I certainly agree that Spaceclaim can produce tight tolerances however there are some modelling features that I could not find in SC which is available in SolidWorks ( probably because of my lack of experience in SC). This is not one off model but around 50 models and much more complext than this configuration. So I prefer to stick to the software that I am competent with given that I have sort time frame. I actually gave up splitting body around weld toes which eliminated all problems

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