Mesh a tube

[transall]

Hi,

I would like to mesh a tube in order to apply a moment on it (the tube is clamp at one end). I thought to use 3D elements but all these elements don't have rotation as degree of freedom, consequently I have no results(no displacement).

That's why I would like to use a 2D mesh but I don't know what elements I have to use, because for example I could drag plane 42 with solid 45 but there is no rotation as degree of freedom.

I made a 1D analysis using beam 188 where I have all the six degrees of freedom, but as several tube are then welded on this tube I need a 3D modeling to simulate the link between the tubes.

Thanks for your Help,

Mickaël

 

[meshparts]

Hello,

normally I would use the SHELL63 (linear) or SHELL93 (quadratic).

Plane42 Elements are not good, since they work only on plane and have only 2 DOF's: UX and UY.

Regards,
Alex

 

[transall]

Hi Alex,
So I can drag Shell 93 or 63 along the tube using 3D elements as solid 45?
I try to do it on a simple square beam defining a shell 93 with a samll thickness. But I have errors with my constraints and loads: "Warning: Specified Specified DOF constraint ROTX at unused node ..." for example.It seems I have this warning for all the nodes where constraints are applied.

Regards,
Thank you,

Mickaël

 

[transall]

Moreover the result is quiet strange as if there were no links between each element.

thank you

Mickaël

 

[cbrn]

Hi,
if the tube is the only model part concerned, then the best you can do, in my opinion, is:
- choose a 2D axisymmetric modellization
- choose an "axi-harmonic" element type (see Manual for elems supporting it)
- set the harmonic index as needed, load as needed (see Manual, key for search "axisymmetric elements under nonaxisymmetric load"

Regards

 

[transall]

Hi,

But the tube is not the only part, it's an assembly of welded tube, so there is no symmetric axis.

Have you some idea how to resolve this problem?

thank you

Regards,

Mickaël

 

[meshparts]

I don't quite understand, why you must drag elements. Probably because the tube is not straight...

Anyway, if you wand to drag elements into shells, then you must model the cross section of the tube using lines and line elements (mesh200,0 or mesh200,1) and then use the ADRAG command to extrude geometry and elements.

Hope it helps.

 

[transall]

Actually, I tried to modelise the tube with an area(9 mm diameter), then I meshed it using shell 93 with a thickness of 2mm to have a an outer diameter tube of 20mm and a tickness of 2mm, because it seems the thickness is spread. But I have warning about the radius of curvature when I solved it.

Thank you,

Regards,

Mickaël