Membrane Elements

Fatmac

I have been experimenting a little with membrane elements on a simple pillow (with a longer term plan to use them to model sails). To use M3D8 elements I had to omit the shell key card add a new *MEMBRANE CARD and introduce a custom card for the M3D8 elements. Is this the best approach, and have I missed anything? When the model uses membrane elements the max deflection is some 50% greater - this sounds reasonable to me but do others feel this is likely??

Victor

There have been bugs with membrane elements in CCX so be careful. That's why it's not enabled in the GUI.

You can use CCX -> custom element type to change quad8 to M3D8 so you don't have to rewrite all the element definitions.

Fatmac

I could not make the membrane work without defining the section as a *MEMBRANE card and disabling the *SHELL card. See attached file. I now think that part of the difference in the shell and membrane solution is the constraints. I have tied the 2 layers together, i'm think in the shell this may restrict the degrees of rotation between these layers -to get a better comparison I probably need to work on the constarints/boundary conditions

Victor

Yes, you'll have to define *MEMBRANE and disable *SHELL like you did. I wasn't sure you'd used custom element type, that's all. It looks like you have membrane working fine. I'm not sure what the bug was or if it's still present.