- Mo 8. Apr 2013, 15:59
your idea with the table is pretty good but let me give some deeper going explanations:
Basically, you may mix elements which feature the same type of dof. The number of dof may vary, however. As a matter of fact, this is true for most of the commercial FEA programs (sometimes they use so-called link elements for combining different element types but I think that's a no-good idea). Thus you may mix in Z88Aurora and Z88V14:
- Hexahedrons No.1&10 with Tetrahedrons No.16&17 with Trusses No.4 with Volume Shells No.21 & No.22 because every node has 3 dof ux, uy and uz. Beam No.2 should work, too, because the first 3 dof are in line with the dof of tetrahedrons, hexahedrons and trusses. Please note to define the entry "6" for nodes which are connected to beams no. 2 and, say, hexahedrons no.10 --> the higher number of dof counts. And be sure to give the correct (i.e. enough) boundary conditions for such nodes. A typical case is, to use trusses no.4 as "spring" or elastic boundary conditions for the volume elements.
- Plane Stress Elements No. 7 with No. 11 with No. 14 with No.3 with Truss No.9 because every node has 2 dof ux and uy. For beams no.13, see above.
- Torus Elements No.8 with No.12 with No.15 with No.6 because every node has 2 dof uradius and uheight. Thus, they cannot combined with other element types.
- Plate Elements No.18 with No.19 with No.19. You cannot combine plates (dof: uz, thetax, thetay) with, say, hexahedrons and tertahedrons (dof: ux, uy, uz). And this would make no sense in any way: plates are 2D elements (they are geometrically only defined by x and y coordinates but the first defection goes into z direction) while tetrahedrons and hexahedrons are really 3D elements (they are geometrically defined by x, y, and z coordinates).
- Shell elements No.23 & No.24. Basically, you could combine volume elements (dof: ux, uy, uz) with, say, hexahedrons and tetrahedrons (dof: ux, uy, uz and thetax, thetay, thetaz). But I would not recommend this: Try to imagine this case geometrically, i.e. how to connect the elements in reality. And because thetax and thetay are global dof it would be rather difficult ot apply correct boundary conditions. Thetaz is quite useless; it's a so-called pseudo (or zombie) dof.