CAD software

Mesh generators, CAD programs, and other tools

CAD software

Postby musquida » 02 Sep 2011, 12:28

Which CAD software would I use for Custom Wheel design for Automotive? It must be used friendly. I have never used CAD before so something easy would be great. Thanks for the help.
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Last edited by musquida on 09 Sep 2011, 09:11, edited 1 time in total.
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Re: CAD software

Postby studioa » 06 Sep 2011, 03:53

If you are looking for Open Source try FreeCAD, then export to gmsh, Salome, EnGrid, Discretizer, ELMER, ...

You can generate 2D production drawings with DraftSight by Dassault Systemes (it is freeware, runs on Windows, MacOS X and Linux).

Or going Open Source for 2D you can use LibreCAD/QCAD.

Also, though it is not CAD, you can use Blender, but the learning curve is steep as the interface is not common to other packages.

In Blender 2.49 you can install the two scripts that are bundled with EnGrid and export your meshes as .gmsh or direct to .begc (EnGrid).

.gmsh files generated in Blender are imported really nice in Elmer, similarly .begc are imported very well in EnGrid 1.2/1.3
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Re: CAD software

Postby moe69 » 13 Sep 2011, 12:21

Hi there,

i am totaly new to Elmer and i got several questions.

1. I want to use FreeCad to design 3d models with multiple bodies. When i save my model, what kind of file typ should i use?
2. I need a software to generate a mesh. Which software is able to save a mesh with multiple bodies to open it in Elmer? What kind of file typ is it?

For example:

I want to simulate heat extension of two different materials, i.e. iron and aluminium. (like a bimetal stripe) - so those two materials will start to bend.

Is this possible to simulate in Elmer?
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Re: CAD software

Postby raback » 13 Sep 2011, 13:23

Hi

Simulation of the case should be possible. For meshing you could have a look at gmsh and netgen, for example.

-Peter
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Re: CAD software

Postby mzenker » 13 Sep 2011, 13:54

If you have two bodies with a common interface, make sure that the mesh is conformal, i.e. the volume elements share faces at the interface. CAD programs often do export separate faces for each body. gmsh and netgen are known to have difficulties to resolve this when it comes to complex geometries.

Matthias
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Re: CAD software

Postby moe69 » 13 Sep 2011, 14:13

hi matthias,

is there a tutorial for generating volumes with shared faces? which cad program do you use?
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Re: CAD software

Postby mzenker » 13 Sep 2011, 14:56

We use Solidworks which has this problem when exporting to STEP format. For simple cases, gmsh can do a cleanup (check Tools->Options->Geometry->General->Cut and merge faces before opening your geometry file). You can also create simple geometries with gmsh. For more complicated cases, there is no opensource solution that I know of. I am working on a solution which is not mature yet.
I don't know of a tutorial.

Matthias
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Re: CAD software

Postby studioa » 21 Sep 2011, 22:08

A path that I use (OpenSource) is:

Blender->EnGrid->ELMER

For Blender 2.49b you can copy-paste the scripts from EnGrid to save as .msh or .becg

Sometimes you need to check/repair the mesh in FreeCAD, then re-import in Blender, but usually works ok. Also you might look at OpenFlipper to repair/decimate the mesh.

In EnGrid you will generate the surface mesh and volume mesh, then you import in ELMER and continue with solver, boundary conditions, material, etc.

The good thing about Blender is that has great mesh generating/manipulation tools. With little care you can generate "anything" you want.
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Re: CAD software

Postby mzenker » 22 Sep 2011, 09:46

Hi studioa

Do you think any of the tools you mentioned can generate a conformal mesh from STEP data containing several bodies with duplicated interfaces and a small overlap (see attachment for an example)?

Matthias
Attachments
Baugruppe1_overlap.STEP
(127.22 KiB) Downloaded 123 times
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Re: CAD software

Postby studioa » 22 Sep 2011, 19:01

Matthias -

your file imports well into FreeCAD - I do not use FreeCAD in a daily basis, but from my experience with it, it is very capable piece of software - though not complete yet - of course doesn't have all the tools that a proprietary package has - you might look also at HeeksCAD/HeeksCNC as an alternate - the model in your example can be generated in Blender, no doubt about that - just that is not going to be a parametric shape, so that might be a drawback - there is a plugin in Blender that allows for generation of parametric shapes, but I have not explore it - if you just want to give it a spin see how the whole workflow is, you can import in Blender (as .stl) the file from FreeCAD (that imports natively .step) and play with it - then you can export to EnGrid and generate the mesh for cfd. - - attached are the screencaptures.

regarding your q. about "conformal mesh from STEP" - I think that the mesh generated by EnGrid is "conformal".
Attachments
EnGrid_import_begc.jpg
(176.77 KiB) Not downloaded yet
Blender_249b_import_step.jpg
(799.56 KiB) Not downloaded yet
FreeCAD_import_step.jpg
(133.14 KiB) Not downloaded yet
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