3. Generalities#

In the documentation for this command, we will talk about:

  • macro element: macr_elem_stat or macr_elem_dyna object,

  • super-mesh: geometric entity supporting a macro_element,

  • initial mesh when we designate the mesh that was used to generate a macro-element,

  • final mesh to refer to the mesh produced by this order.

By extension these adjectives initial/final will apply to entities attached to meshes: node, mesh, group of nodes.

Practically, to build the final mesh:

  • supermeshes are defined by positioning existing macro-elements in space (2D or 3D) (the same macro-element can generate several supermeshes),

  • we glue the supermeshes together,

  • we rename, if we want, some nodes,

  • we create, if we want, certain groups of nodes.

Notes:

It can be seen that the mesh created by this command is only formed of supermeshes. It is therefore not possible (for example) to draw it with the usual postprocessors. Possibilities to remedy this may exist with the command DEFI_SQUELETTE [U4.24.01].

To mix « classical » finite elements and substructures, you must use the mesh « concatenation » operator [U4.23.03]: mag = ASSE_MAILLAGE (MAILLAGE = (m1, m2)))

A mesh resulting from operator DEFI_MAILLAGE contains:

  • supermeshes,

  • knots,

  • node groups.

Supermeshes are defined by translation/rotation of macro-elements.

Like a « classic » mesh, a supermesh is entirely defined by the list of its knots. The coordinates of the mesh nodes are those of the external nodes of the macro-elements transformed by the geometric transformation: translation, rotation…

If no gluing is performed (see RECO_GLOBAL/RECO_SUPER_MAILLE), the mesh has as many nodes as the sum of the nodes of the supermeshes.

Convention C1:

When you « glue » the superstitches back together, you eliminate some knots. By convention, when eliminating coincident nodes, we keep the node (and therefore its coordinates) that comes from the first mesh of the l_mail list (see RECO_GLOBAL/RECO_SUPER_MAILLE).

As in any Aster mesh, the nodes are named. By default, node names are given by the program in the form: Nijk where ijk is a number between 1 and 999999.9.

The DEFI_GROUP_NO keyword allows the user to rename certain nodes and define groups of nodes.