"Iglu" shell benchmark

[pablobecker]

Description Running the "half spherical shell" benchmark I am getting very bad results for an acceptable mesh. With a 8x8 mesh in a 1/8 sphere, I am getting half the expected displacements, but according to the papers it should be much better ( see Analysis of plates and shells with a simplified three node triangular element ). I ran the full example, to avoid possible problems with the symmetry. Results with the thin element are even worse. Using 12 divisions the result is much better.

EDIT: Incorrect load (1/2) in the 8x8 case. So results of the thick element are good. Only problem is with the thin element

Scope Structural Mechanics App

Attachments: kratos_files_8divisions.zip iglu_12.zip

[loumalouomega]

Have you tried with quad elements?

[pablobecker]

not yet. but in principle, even the tria3 should be way better

[rickyaristio]

I found one problem in kratos_files_8divisions.zip. The load magnitude should be doubled (F = 2, instead of 1) as we model the whole sphere.

Source: Stress projection for membrane and shear locking in shell finite elements - see Table 3.

[pablobecker]

ouch! you're right! i feel extremely stupid at this moment. thank you!!

[pablobecker]

any idea why the thin element is so rigid?

[rickyaristio]

any idea why the thin element is so rigid?

I have a similar problem. The thin element uses DKT as well, so I expect to get results similar to the paper you mentioned.

Let me try to investigate it.