Mesh help for Cross beam structure (using shell element)

msy288

Gents, I am doing some example related to my work in Mecway and I am modelling a cross H beam structure (pls see the attached screenshot). I am using all shell (2D) elements. I find it very time consuming to do the mesh in Mecway because I have to do a lot of extruding/sweeping to ensure that the intersection of the two H beams are connected to each other perfectly. I remember that in ANSYS I can just did the geometry in designmodeler and group them before sending to mesh module. Then ANSYS mesh module will automatically recognize the contact area. I understand that I should not expect the same level of functionality since Mecway is significantly less expensive than ANSYS.

After doing some research I downloaded the Gmsh and Salome. I played Gmsh a little bit and find it not very user friendly. I didn't get a chance to try the Salome but it looks more user friendly than Gmsh. I am only targeting to do some analysis similar to the cross beam structure as shown in the attached screenshot. Could you please advise how should I make the meshing part easier? Thanks!

Victor

I would do it like this:

1. Start with a refined 2D plate for the plan of the whole structure.
   
2. Delete elements for the holes (shown partially done in the picture).
   
3. Adjust rows of coordinates at a time to position everything correctly.
   
4. Refine x2 the remaining flanges so they all have a line of central nodes.
   
5. Extrude all the webs in single operation.
   
6. Move/copy to duplicate the flange.
   

It took a minute or two to make this partial model. I skipped some of the webs:

cwharpe

Hope I'm not over-simplifiying your issue, but I've always modeled welded frames like a sandwich.

Using Mecway tools, I create the shell footprint of all bottom flanges joined together. Often this begins in the form of several rectangles, and using the Refine/Custom mesh tool is a great advantage. Some attention is required to insure the mesh will provide nodes at the web centerlines.
Once the bottom flanges are saved (Named Selection), the web cL nodes are chosen, then reselected as faces, then extruded in normal direction. Lastly, Flanges group is copied to Top flange position, and all nodes merged together. If in subsequent editing I've copied elements to other locations, the "Find duplicate elements" is a valuable mesh check.

Alternatively, extruding a single beam from a cross-section, then using that "Parent" to copy, rotate, mirror it's "children" into the form of your structure -- would definitely appreciate "Find duplicate elements" after merging nodes.

cwharpe

Ha! @Victor beat me to the punch. Couldn't resist getting up for that snack....

Victor

Haha and incredibly similar too!

msy288

Hi Victor, thank you very much! That is such a genius way to get it done quickly!

msy288

Thanks cwharpe! That is also a great method!