Dear Discourse Group,
I have created this simple shell model, but when I turn on NLGEOM, the simulation diverges. It is quite a simple model, without contacts and using only plasticity.
I would like to post the gz model (only 14kB), but I can’t figure out how to do it.
In the image the solution whitout the NLGEOM=ON
Any ideas?
You can use some hosting service and share the link here.
Are you using rigid body constraints ? They are known to cause convergence issues when used with shells and Nlgeom.
If that deformation is real scale I would also perform a Linear buckling analysis to see if it could be buckling.
You caught the target! I’ll avoid to use *rigid to apply load and constraints and let you know
Thank you, it solved my simulation. But you also know the theoretical reason? Does it matter on how the shell are expanded in CalculiX?
rigid body and shell element in CalculiX is a bit different, edge clamping not restrained and may cause a problem in case of geometric nonlinearity and material plasticity.
It is magnified of about x50
Guido (ccx dev) explained it here: Rigid-body constraint convergance problems - #25 by dhondt
