Thick shell for FEA modes analysis 2

[jungi]

Hallo everbody,

i'm looking for someone, who has experience in using thick shell elements in FEA normal modes extraction. I've just compared volume to thin shell and it's a dissaster .

Especially using quadrilateral shell elements (!) i obtain different results computing the same mesh using Lanczos solvers from different commercial packages (ideas, Ansys) I get discrepancies up to 40Hz!. I wonder if thick shell formulation would be a better substitute for volume modelling (computational time) than thin shell meshes?

thanks in advance for any suggesrtions!

greetings

Artur

 

[jungi]

Anyway it shouldn't show such differences - and as I said before I always use the same model! The type, size and order of form function are exactly the same!!! I compared the formulation for different software using their theoretical manuals they are all the same!!! And still if by any chance the interpretation is different, so I still can't understand those vast differences that occur.

 

[pja]

If you don't know what a DKT formulation is (which is the formulation SHELL63 uses) then you didn't read the manuals that closely...what happens if you compare results from SHELL63 and SHELL181 in ANSYS?

 

[jungi]

…my preprocessor uses elements called TRIA6, 6-Nodes, 6-DOF (second order shell element) they are converted into SHELL 93 for ANSYS and type ID 92 (universal file description) for Ideas, both 6-Nodes, 6-DOF… I’ll conduct the comparison between SHELL63 and SHELL181 for Ansys… I’ll post here the results when ready…

Regards

 

[PulseMaster]

I've had good luck with ansys solid shell 190s for a wide range of shell thickness. They are available in workbench also.