3. Operands#

3.1. Keyword factor CLASSIQUE#

♦/CLASSIQUE = _F (

Keyword factor for the definition of a modal base of type” CLASSIQUE “, when performing a calculation by dynamic substructuring.

3.1.1. Operand INTERF_DYNA#

Interf_dyna_clas type concept name produced by DEFI_INTERF_DYNA [U4.64.01].

The operator calculates the static deformations corresponding to the various interfaces defined, based on the numbering used for the calculation of the natural modes.

3.1.2. Operands MODE_MECA/NMAX_MODE#

List of mode_meca concepts containing the specific modes of the structure.

List of integers giving, for each mode_meca concept, the maximum number of specific modes to remember. Starting from the th modal base of the mode list, the modes corresponding to the nbmodes [i] lowest frequencies are then retained.

In general, the length of the integer list, entered under the keyword NMAX_MODE, must match that of the list of modal bases (keyword MODE_MECA). The only exception to this rule is when a single value is given in NMAX_MODE. In this case, the value of NMAX_MODE is used for each of the modal bases.

If NMAX_MODE is not entered, all the modes in each of the modal databases given under the MODE_MECA keyword are taken by default.

3.2. Keyword factor RITZ#

♦/RITZ = _F (

Key factor allowing:

  • in the case of a calculation by substructuration, to build a modal substructure base of the type “RITZ”;

  • in the case of a calculation directly with the complete structure, to build an enriched modal base (for example: natural vibration modes, which are enriched with static modes associated with external forces).

The base is constituted in two different ways: either from two occurrences of the keyword RITZ (one with the keyword MODE_MECA or BASE_MODALE, another necessarily with the keyword MODE_INTF, the other possibilities are not authorized); or from a single occurrence of the keyword RITZ and only the keyword MODE_MECA is then accepted (rarely used except possibly to reduce the number of modes (or change the reference numbering).

3.2.1. Keyword MODE_MECA#

Name of the mode_meca concept containing the natural vibration modes of the structure, or of the substructure in the case of a calculation by substructuration.

It can be used alone or in the presence of a second occurrence of RITZ with the MODE_INTF keyword (if you want to add interface modes for example).

We can give a list of mode_meca obtained for the same structure (with different boundary conditions for example).

3.2.2. Keyword MODE_INTF#

Name of the mode_meca type concept (produced by CALC_MODES [U4.52.02] or by MODE_STATIQUE [] or by [U4.52.14]) or mult_elas (produced by MACRO_ELAS_MULT [U4.51.02]) containing:

  • in the case of a calculation by substructure: the modes that we want to use as interface modes of the substructure;

  • in the case of a calculation directly on the complete structure: modes that enrich the base of natural vibration modes given under the previous MODE_MECA keyword. This can for example be static deformations associated with external forces (known imposed force; shock force associated with an obstacle; etc.).

It can only be used in the presence of a second occurrence of the keyword RITZ which will contain the keyword MODE_MECA or BASE_MODALE (even if you do not want to take this keyword into account for example). NMAX_MODE

3.2.3. Keyword BASE_MODALE#

Mode_meca concept name produced by a previous call to the DEFI_BASE_MODALE operator [U4.64.02]. It can only be entered when the number of occurrences of the RITZ keyword is equal to two. The other occurrence of the RITZ keyword will then necessarily contain the MODE_INTF keyword (to enrich an existing database). The concept name mode_meca resulting from the operator may be different from this one or identical (it is then reentering).

3.2.4. Operand NMAX_MODE#

Number of modes to remember in the dynamic (or static) modes given by one of the previous keywords under the occurrence of the keyword RITZ. If you enter a list of modes_meca, you must give either a list of the same size for the number of modes to remember, or a single value (in this case, this value is applied to all the mode_meca concepts).

If NMAX_MODE is not entered, all modes are used by default.

3.2.5. Operand INTERF_DYNA#

Dynamic interface of the substructure (to be filled in if necessary and only if the keyword factor “RITZ” is used).

3.2.6. Operand NUME_REF#

Reference numbering on which all the displacement fields (dynamic and static modes) forming the basis of “RITZ” will be reordered.

3.2.7. Operand LIST_AMOR#

List of modal depreciations that the user can provide to enrich the modes declared under the keyword MODE_MECA. This is equivalent to adding reduced depreciation for these modes even if they are real modes at the origin. This option is useful for simulating experimental results.

3.2.8. Operand ORTHO#

Operand allowing to orthonormalize the Ritz base (to be filled in if you want this re-orthonormalization and only if you use the keyword factor “RITZ”). This orthonormalization is done with an iterative Graam-Schmidt algorithm (IGS) according to the Kahan-Parlett version.

3.2.9. Keyword MATRICE#

Name of the matr_asse_* concept that will be taken into account for dot products when reorthonormalizing the base of RITZ. It is a mandatory keyword if ORTHO =” OUI “.

3.3. Keyword factor DIAG_MASS#

♦/DIAG_MASS = _F (

A keyword that allows static modes to be recalculated by eliminating the dynamic contribution and performing Graam-Schmidt orthogonalization.

3.3.1. Keyword MODE_MECA#

Name of the mode_meca concept containing the dynamic eigenmodes of the processed substructure.

3.3.2. Keyword MODE_STAT#

Name of the mode_meca type concept produced by the MODE_STATIQUE [U4.52.14] operator that contains static modes.

3.4. Keyword factor ORTHO_BASE#

♦/ORTHO_BASE = _F (

Keyword used to orthonormalize the modes of a database This orthonormalization is done with an iterative Graam-Schmidt algorithm (IGS) according to the Kahan-Parlett version.

3.4.1. Keyword BASE#

Name of the mode_meca or mult_elastype concept containing dynamic eigenmodes.

3.4.2. Keyword MATRICE#

The name of the matr_asse_* concept that contains will be taken into account for dot products during reorthogonalization.

3.5. Keyword factor SOLVEUR#

◊ SOLVEUR = _F (…)

This factor keyword is optional: it allows you to choose another system resolution solver. In the case of this command, the keyword syntax is restricted to two methods: you can choose between the default method, MULT_FRONT, and the LDLT or MUMPS methods. Since the syntax is common to several commands, please refer to the [U4.50.01] manual.

3.6. Operand TITRE#

◊ TITRE = title

Title of the concept created.

3.7. Operand INFO#

◊ INFO =

Level of information provided in file MESSAGE:

1

no printing;

2

writing generalities (upstream concepts, base type).