Simulation Mechanical and Multiphysics

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Member
rtagomes
Posts: 5
Registered: ‎02-08-2012

Mesh geometry

685 Views, 4 Replies
02-23-2012 02:02 AM

Hi there,

 

I am using Algor Simulation Professional 2011 and trying to use a mesh brought in from Rhino as STL. Problem is relatively simple: I would like to work with a 'diamond shape' mesh (actually, just squares rotated by 45 degrees).

 

Since I could not find how to mesh in such geometry in Simulation, I figured it would be best to bring the mesh already created. The issue is that once I do so, the mesh is further triangulated once in Algor and does not behave as a normal mesh (cannot select edges or complete surface parts within the model). Furthermore, I can also not perform analysis as I get the error 0x13C5.

 

Is there a way of using this imported mesh or to create a similar type mesh in Algor?

 

Attached a couple of JPEGS with what I would like to achieve.

 

Thanks,

Ricardo

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Employee
INACTIVE_AstroJohn
Posts: 492
Registered: ‎03-25-2010

Re: Mesh geometry

02-23-2012 05:26 AM in reply to: rtagomes

Hi Ricardo,

 

I believe that Rhino is creating the triangular mesh because that is the definition of an STL file -- a surface composed of triangles. So a couple of options come to mind (depending on the geometry):

 

1) Can you save the Rhino model to another format, something that exports the lines but not the surfaces? For example, DXF, wireframe IGES, or AutoCAD DWG formats are pure lines and can be opened in Simulation.

 

2) The added lines can be selected by using a filter based on the line length. The hypotenuses are longer than the sides of the diamond.

 

To answer some of your other questions,

 

a) Because you are importing lines and not a CAD model, there are no "Edges" in Simulation.

 

b) Please clarify what you mean by "cannot complete surface parts"? From what I see in your images, you want to create plate elements, which by definition are composed of 3 or 4 sided regions. And that is what you have imported.

 

c) Off hand, I do not know what is causing the 0x13C5 error. If you encounter it again after fixing the model, I suggest that you create an archive of the model and post it to a reply. See "Create, Post, or Provide an Archive of your model".

Sincerely,
John Holtz, P.E.
Senior User Experience Designer, Simulation
Autodesk, Inc.

Current version of Mechanical & Multiphysics: 2013 SP1 (2013.01.00.0012 28-Jun-2012)
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Member
rtagomes
Posts: 5
Registered: ‎02-08-2012

Re: Mesh geometry

02-24-2012 02:52 AM in reply to: INACTIVE_AstroJohn

Hi John,

 

Thanks for your quick reply.You are right, probably the extra triangulation is happening when writing the STL. Problem is that I cannot export this mesh using any of the other type files Algor imports as it is not a closed mesh.

 

a) & b) When I import a similar model from Rhino using the Algor plugin (and mesh it within Algor) I am able to select different surfaces within my model (it has 3) and assign them loads sepparatelly. I am also able to select the edges of these surfaces and give them boundary conditions. The STL does not let me select edges or sepparate parts - onle the full element.

 

c) The error says that Algor cannot perform the selected analysis. I will try the solution above and see if this is still a problem. 

 

1) I will use your suggestion and export lines from Rhino. If I take in lines only am I able to mesh them in Algor? How will this be done?

 

Many thanks,

Ricardo


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Member
rtagomes
Posts: 5
Registered: ‎02-08-2012

Re: Mesh geometry

02-24-2012 06:26 AM in reply to: rtagomes

Had another go - I can export the mesh to DXF but not open it with Algor - tells me 'no solid to import'.

The lines it is no problem, I can bring them into Algor as DXF but I cannot work out how to use them to create a mesh...

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Employee
INACTIVE_AstroJohn
Posts: 492
Registered: ‎03-25-2010

Re: Mesh geometry

02-24-2012 06:55 AM in reply to: rtagomes

Hi Ricardo,

 

I thought that your original image "Rhino.png" and the image from Simulation indicated that you already had a mesh created. In other words, a mesh is just a bunch of lines connected together to create the proper elements! Whether you are importing a CAD model and using the automatic mesher to create the lines, or importing a "mesh" from another source to create the lines, or drawing each and every line one by one, as long as you have 4 lines connected together, you have created a plate element. (I am just guessing that you are wanting to create plate elements.)

 

If the lines in Rhino are not split to create 4 sided elements, then you can intersect them in Simulation. But it is probably much easier to split the lines in Rhino.

 

When importing a CAD model, the software automatically assigns different faces to different surface numbers and creates edges. You are essentially creating a hand-built model, and hand-built models do not have an edge property. But you can select the lines ("Selection > Select > Lines") and change the surface numbers ("Draw > Modify > Attributes") to suit your requirements.

 

You may be interested in the example "Help > Autodesk Simulation > Examples > Modeling > Ball in a Box with Body to Body Radiation Model" to get some additional modeling experience with hand-build models.

 

 

Sincerely,
John Holtz, P.E.
Senior User Experience Designer, Simulation
Autodesk, Inc.

Current version of Mechanical & Multiphysics: 2013 SP1 (2013.01.00.0012 28-Jun-2012)
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