[Gmsh] Making a Abaqus/Calculix .inp file, second order quads

[Justin Black]

Hello,
I'm trying to make second order quad elements. Meshing works fine, but when
I export my mesh as the Calculix .inp format, the elements are incorrect.
It makes:

*Element, type=CPS4, ELSET=Surface0
10681, 386, 476, 480, 479, 891, 892, 893, 894, 895

Note that it lists the element number, then 9 nodes, this is incorrect.
CPS4 is made of 4 nodes only and is a first order element.
Instead, a second order quad should have been printed here, a CPS8,
see the line below as a mock-up.

*Element, type=CPS8, ELSET=Surface0
10681, 386, 476, 480, 479, 891, 892, 893, 894

Can the next version of gmsh fix this?
Please make sure and use element numbering as shown in:
http://bconverged.com/calculix/doc/ccx/html/node38.html
Thanks,
-Justin

[Justin Black]

I figured out the answer. I needed to turn on the following gmsh flag to
make the element only have 8 nodes:

Mesh.SecondOrderIncomplete=1; //req for 2nd order, no face node

If this option is not set, the second order quad that gmsh will make has 8
nodes to define the quad element and an additional node in the center of
the face, a total of 9 nodes to define the element.
So always use the above line if you are exporting 2nd order quads to
Calculix/Abaqus.