Shell to Membrane

Fatmac

I have been trying to do some comparison between shell and membrane analysis. When I have simple plate with quad4 elements and I try to use "CCX custom element type"
i get the following error />
*ERROR reading *SHELL SECTION: *SHELL SECTION can only be used for shell or user elements. Element 1 is not a shell nor a user element.
*ERROR in calinput: at least one fatal error message while reading the input deck: CalculiX stops.

I have found a work around by redefining the elements and using the *MEMBRANE SECTION CARDS. I think this them gets me what I after but it does feel like a bit of a work up. I am missing something here.? Do I need to do anything else to be sure I'm modelling membranes as close as possible?
I think the results show the trends I' am expecting but not as large a difference between shells and plates I was expecting. The online calculators I have found don't match up that well with either my shell or membrane results. Are there any reliable bench marks any one can recommend I take a look at

Fatmac

I have stumbled across an excellent collection of bench marks generated by Andrea Starnini - see screen shoot attached. I have really enjoyed going thru some of these examples and wonder if other documents like this are available?
Having work thru many and arrived at the same answers there is one where I think there is a possible type - see attached. I think it may be a 100x50x25 mm plate -not 100x50x2.5. It would also tie in with the analytical solution I found
Be good t know if this is a typo or if I'm really doing something wrong!

disla

That is not a good reference for comparision unless the thickness is very very small so bending stress doesn't have any role.
If you want to test it you better compare using some Catenary example.

Fatmac

Understood, I was using solid elements for that one. I just saw the example and couldn't help but give it a try!
Thanks for pointing it out though