Using Shell elements to model a channel section

[Connor026]

Hi,

Im tring to use shell elements(S4) to simulate the behaviour of a channel section of mild steel. Im using abaqus and I'm having some difficulty with the mesh. I guess my first question is whether the shell thickness is important. After the part is meshed, if I render the shell thickness the mesh shown is completely wrong, whereas the mesh without the shell thickness rendered is exactly how I wanted it. The results I get from the analysis are good and very close to my expected values, however I am still unsure if I am doing something wrong and need to reconsider my mesh.

I hope this makes sense, I have included some screenshots in the attachments to further explain what I mean.

Any help would be greatly appreciated,

Thanks

Connor

 

[Swlamech]

I believe this issue is only graphical, especially if your results are closely matching hand calculations. The software is just trying to build a representation and having problems at the corners.

 

[rb1957]

do i understand that if you mesh the 2D shape, things are good; and things go "pear-shaped" if you try to mesh the solid ?

i'd look into the solid meshing parameters ... TET mesh or brick ? aspect ratio ? number per side ?

it might be a visual problem, or you could examine the elements near the corners, to see if they are as effed up as they look.

another day in paradise, or is paradise one day closer ?

 

[stressebookllc]

Please, use plate elements, if you can use beam elements to account for shear center as well.

http://www.stressebook.com

Stressing Stresslessly!

 

[corus]

It appears that the rendered geometry is taking into account the corner of the channel so that the thickness appears to taper at the corner. The thickness of the shell at the corner is correct if you consider the thickness at 45 degrees to the corner. This will be the same as the thickness of the shell away from the corner. The distance of a line perpendicular to each face at the corner will thus appear to be less than the true thickness.

 

[rb1957]

how exactly did you render the solid ? is it a 3D shape imported from CAD ? is it based somehow on the 2D shape ??

another day in paradise, or is paradise one day closer ?