mesh failure

mattone

Hi All,

I am playing with the last version of Mecway and I bought a LISA licence few years ago. Both software gave me many problems on meshing, in particular when geometry is a mix of shells and solids "in contact" or some assembly of different parts.
I attached a typical example of an imported model that I failed to mesh. This is an assembly of shell and solid parts.

In this case geometry is quite simple (and it fails to mesh) and it can be reproduced in Mecway but often parts received from clients are more complex and the "reproduction" is almost impossible.

Is there a way to solve this problem? Is there a way to import a mesh from some other software (like Netgen or Gmesh)?

Unfortunately if the part cannot be meshed properly, Mecway becomes not useful. Or probably am I asking too much from the software?

Mario

Victor

Hello Mario

Indeed, meshing is a bit of a handicap with Mecway and I regret that it's causing you frustration. It can only do a single solid part in each STEP file. So no assemblies unless each part has its own file and no shells.

Version 3 goes some way to helping with this by having bonded contact to connect incompatible meshes from each part of an assembly. You have to split it up into separate STEP files, so it's only practical for a few parts.

Yes, you can import meshes from Netgen (.vol format) or Gmesh (.msh format).

VMH

Mario, what was your plan for this? investigating the bottom plate and the two hinges? If yes, you can just export those three parts into step files and use bonded contact in Mecway to bond it or you can union them together first and export as one step file. In either case, your model to me will be very difficult to mesh in any software because of the way it was model. It's not quite solid to solid connections and not shell/face also. see attachment.

VMH

Mario, nevermind. It can be meshed. You can mesh it into different part using a meshing software that can mesh it and export the mesh file. Then import each mesh into Mecway. Mecway version 3 has the "bonded contact" that is very helpful in connecting different part together. I would look close at the results at those connections though.

VMH

Mario, I think the assembly needs to be defeatured or removed the small holes and long edges radius which causing the model to be very large when meshing which are not contributing much in the overall results. We can just adjust the meshing parameters to a point but can't do anything more than that.

I made a video on your assembly using three of the parts just an example showing the meshing and bonded contact in Mecway. Displaying the featured edges is one of my favorites in version 3 because displaying the element edges may be too much to view sometime and turning the element edges off makes it hard to see what is what as in previous versions. Mecway is getting better for each release, and it's an affordable option for learning more advanced FEA.

https://www.dropbox.com/s/o8h95c9xuvzirbe/Test Meshing and Bonded Contact in Mecway.mp4?dl=0

mattone

Hi VMH and Victor,

Thanks very much for the time you spent to answer to my post.
So, the way to solve it consists on importing the three parts separately and mesh those once at time. Interesting, I didn't think about it.
Defeaturing models is also a valid option for simple structures or assemblies, less for more complex.
In the meantime I have checked how to export mesh from Gmesh and import in Mecway.
So useful answers and also advices. Thanks to all.
Mario

PS. Bonding contact works only on surfaces or also on edges (lines)??

Victor

Yes, only 2D surfaces for now, not 1D edges.

eric_c

Hello VMH,
Thanks for the video, that is great, there is a lot of usefull information in it.

VMH

Thanks

VMH

Uploaded to YouTube:

Victor

These are some great videos VMH. Do you mind if I add them to Mecway's YouTube channel too?

VMH

Victor, feel free to add any of my videos and also future videos.

johnkent

Very nice: I found the "coil spring" and the recent VMH videos; are there more?

Victor

Here are some other videos that people have made:

Workflow for propeller blades imported from Prop_design. Anthony has done a lot of work to find an easy procedure with good accuracy.
http://code.fosshub.com/PROP_DESIGN/downloads

Importing a CAD part and resolving bad elements in the mesh


A short video of a simple CAD part. This was version 1 of Mecway
http://mecway.com/download/platewithhole.mp4

[Deleted User]

Hi,

Just wanted to say that my screencasts have been updated and are located at;
http://propdesign.jimdo.com/download/

I closed the codeFossHub page.