Clean mode post-treatments
==================================


.. _RefHeading__2622_1246081310:


Visualization
-------------

The modal deformations calculated by one of the methods described above can be exported in various formats in order to be visualized in mechanical calculation platforms: format MED for the Salomé platform, format UNV,...

The user can thus graphically characterize the calculated modes: bending mode? fashion in a given plane? local fashion? etc.

**Example:**

printed in MED format.

modes = CALC_MODES (...) # modal calculation

IMPR_RESU (FORMAT = 'MED',

RESU =_F (RESULTAT = modes));

We can then open the file created in the Salomé platform to visualize the modal deformation, animate it,...


.. image:: images/10000000000001810000028154051956C36A19F5.png
    :width: 2.3957in
    :height: 3.989in


.. _RefImage_10000000000001810000028154051956C36A19F5.png:

**Figure** 5.1-a **: Visualization of a mode in Salome (ParaVis module): here the 2nd order bending mode of a beam.**




Normalization of modes
-----------------------

Modal deformations are defined with one multiplicative factor (see formulation of the modal problem in paragraph :ref:`1 <RefNumPara__10834_1246081310>`).

By default, the modes calculated by the CALC_MODES operator are normalized so that the largest physical component is equal to 1. The user can modify this normalization, either directly in the operator CALC_MODES using the keyword factor NORM_MODE, or later using the operator NORM_MODE [:external:ref:`U4.52.11 <U4.52.11>`]. In both cases, the code also calculates or updates the following modal parameters, which depend on the normalization chosen: FACT_PARTICI_D *, MASS_GENE, and RIGI_GENE. It also enriches the data structure with the MASS_EFFE_UN_D* parameters (which are independent of normalization). These parameters (defined in paragraph :ref:`4 <RefNumPara__1977_654154550>`) can be useful in particular to eliminate certain unwanted modes from a modal basis (see paragraph :ref:`5.3 <RefNumPara__1931_654154550>`).

**Example:**

norm in relation to mass.

1st possibility:

modes = CALC_MODES (MATR_RIGI = matr_k,

MATR_MASS = matr_m,

OPTION = 'BANDE',

CALC_FREQ =_F (FREQ = (20., 300.)),

NORM_MODE =_F (NORME = 'MASS_GENE')

)

2nd possibility:

modes = CALC_MODES (MATR_RIGI = matr_k,

MATR_MASS = matr_m,

OPTION = 'BANDE',

CALC_FREQ =_F (FREQ = (20., 300.)),

)

modes = NORM_MODE (reuse = modes,

MODE = fashion,

NORME = 'MASS_GENE');




.. _RefNumPara__1931_654154550:


Filtering modes according to a criterion
-----------------------------------

In the perspective of a transient response calculation, for example, the user may choose to keep in his modal projection base, only certain modes considered important in the dynamic response or meeting a given criterion. This can be done either directly in CALC_MODES with the keywords factors FILTRE_MODE and IMPRESSION, or using the EXTR_MODE [:external:ref:`U4.52.12 <U4.52.12>`] operator. We can thus filter the modes according to various options: from their number in the global spectrum, from their generalized mass, etc.

**Example:**

elimination of modes whose effective unit mass is less than 5%, and display in file RESULTATdu the cumulative effective unit masses of the retained modes.

1st possibility:

modes = CALC_MODES (MATR_RIGI = matr_k,

MATR_MASS = matr_m,

OPTION = 'BANDE',

CALC_FREQ =_F (FREQ = (20., 300.)),

NORM_MODE =_F (NORME = 'MASS_GENE'),

FILTRE_MODE =_F (CRIT_EXTR = 'MASS_EFFE_UN',

SEUIL = 0.05),

IMPRESSION =_F (CRIT_EXTR = 'MASS_EFFE_UN',

CUMUL = 'OUI'),

)

2nd possibility:

modes = CALC_MODES (MATR_RIGI = matr_k,

MATR_MASS = matr_m,

OPTION = 'BANDE',

CALC_FREQ =_F (FREQ = (20., 300.)),

NORM_MODE =_F (NORME = 'MASS_GENE'),

)

modes_f = EXTR_MODE (FILTRE_MODE =_F (MODE = modes,

CRIT_EXTR = 'MASS_EFFE_UN',

SEUIL = 0.05),

IMPRESSION =_F (CRIT_EXTR = 'MASS_EFFE_UN',

CUMUL = 'OUI'),

);

**Note:**


* *The operator* *EXTR_MODE allows you to filter with a threshold applied to one or more given directions (keyword* *SEUL_Xpar example for the DX direction), which is not possible directly in* *CALC_MODES currently.*