3. Operands#

3.1. Operand NUME_DDL#

♦ NUME_DDL = naked

The name of the nume_ddl concept for the structure.

3.2. Keyword INTERFACE#

♦ INTERFACE

Key word factor for defining interfaces.

3.2.1. Operand NOM#

Interface name. It is mandatory for each interface. If for an occurrence of the keyword factor INTERFACE no name is given, then this occurrence complements the definition of the previously named interface (concatenation of the list of nodes after those already existing). This makes it possible to use the keyword GROUP_NO for the same interface, or to give different arguments to the keywords MASQUE and DDL_ACTIF within the same interface.

3.2.2. Operand TYPE#

It allows you to specify the genre of the modal base corresponding to the interface.

interface corresponding to a modal base of type MAC - NEAL which includes specific modes and attachment modes. The attachment modes are only counted, at the interface, on the degrees of freedom that are not blocked and not hidden.

interface corresponding to a modal base of type CRAIG - BAMPTON which includes natural modes and constrained modes. Constrained modes are only counted, at the interface, on the degrees of freedom blocked by dualization and not masked.

interface corresponding to a modal base of the CRAIG - BAMPTON harmonic type that includes natural modes and constrained harmonic modes (imposed harmonic unitary displacement). The frequency used is the one given as an argument to the keyword frequency “FREQ”.

Harmonic constrained modes are only counted, at the interface, on the degrees of freedom blocked by dualization and not masked.

free interface. No static deformations will be calculated; the modal base will only include natural modes.

3.2.3. Operand GROUP_NO#

An ordered list of the groups of nodes in the mesh that make up the interface. The final list of nodes is obtained by uniting the groups of nodes in the order given by the user, when defining the groups.

3.2.4. Operand MASQUE#

List of ddls for the nodes that should not cause static deformations (hidden ddls).

3.3. Operand FREQ#

◊ FREQ = val_freq

Frequency value used for the calculation of harmonic constrained modes.

3.4. Operand INFO#

◊ INFO =

Level of information provided in file “MESSAGE”:

1	no printing,
2	writing the definitions of the interfaces (genre, nodes), and the static deformations identified (allows you to check the list of static deformations before their actual calculation).

3.5. Case of a node common to several interfaces#

When a node is common to several interfaces (for example the center of a circular structure), this often leads to a singular system in calculating the eigenmodes of the complete structure. We get around this problem by eliminating the common thread. This of course leads to an error on the global modes but if the mesh is quite fine, it is not sensitive (see test case SDLS01).