D modeling
==============


Characteristics of modeling
-----------------------------------

Elements MECA_HEXA20, MEFL_HEXA20, MESF_QUAD8


.. image:: images/1000000000000119000000BCE6C09ED92B029E38.png
    :width: 2.928in
    :height: 1.9583in


.. _RefImage_1000000000000119000000BCE6C09ED92B029E38.png:

Boundary conditions:

In all the knots on the face :math:`M`

.. code-block:: text
 DDL_IMPO: (GROUP_NO): knot/surf PRES: 0. PHI :0.)

In all the nodes of the piston

.. code-block:: text
 (GROUP_NO: noeupist DY: 0. DZ:0.)


Characteristics of the mesh
----------------------------


.. csv-table::

    "Number of nodes:", "201"
    "Number of meshes and types:", "24 HEXA20, 8 QUAD8"



Tested values
---------------


.. csv-table::

    "**Frequency**", "**(** :math:`\mathit{Hz}` **)**", ""
    "**Reference**", "**Aster**", "**Error (%)**"
    "13.8285", "13.8277", "-0.006"



notes
---------

Mode calculations performed by:

.. code-block:: text

    CALC_MODES
OPTION =' AJUSTE ',
CALC_FREQ =_F (FREQ =( 10.,20.))

The analytical solution of the first eigenvector is not known.

**Contents of the results file:**

Value of the first natural vibration frequency of the coupled system.