C modeling
==============


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


.. image:: images/10001E70000069D500002D10A1C295348BA567FD.svg
    :width: 552
    :height: 235


.. _RefImage_10001E70000069D500002D10A1C295348BA567FD.svg:

We are testing the DKT model with TRIA3 meshes. The same boundary and symmetry conditions are applied as in models A and B.

The successive states of equilibrium are obtained using an arc-length control method.

In this case ETA_PILOTAGE = :math:`\frac{p}{{p}_{\mathit{max}}}`


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

Number of knots: 121

Number of meshes and type: 200 TRIA3

Since there are fewer points on the TRIA3 mesh type compared to TRIA7 and QUAD9, we refine the mesh (10x10 meshes).


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


.. csv-table::

    "**Identification**", "**Instants**", "**Reference**", "**Aster**", "**% difference**"
    "Limit point no. 1", "", "", ""
    "DZ", "1.03", "—0.0131", "—0.01314", "0.312"
    "Eta_ PILOTAGE ", "1.03", "0.9916", "0.9818", "0.987"
    "Endpoint No. 2", "", "", "", ""
    "DZ", "1.78", "—0.0170", "—0.0170", "—0.01704", "0.208"
    "Eta_ PILOTAGE ", "1.78", "0.15", "0.1072", "28.55"
    "Endpoint No. 3", "", "", "", ""
    "DZ", "2.34", "—0.0140", "—0.0140", "—0.01435", "2.511"
    "Eta_ PILOTAGE ", "2.34", "—0.4000
    —0.4916", "—0.5461", "11.08"
    "Endpoint No. 4", "", "", "", ""
    "DZ", "2.50", "—0.0161", "—0.0161", "—0.01584", "1.606"
    "Eta_ PILOTAGE ", "2.50", "—0.6333", "—0.6426", "1.462"



notes
---------

The calculation strategy used is divided into two steps:


* calculation under imposed load up to :math:`P=\mathrm{582.N}` corresponding to 97% of the critical load,


* "imposed displacement" calculation: then, an imposed displacement is imposed using the technique of the arc length imposed on the entire structure (option LONG_ARC in STAT_NON_LINE).

Using the arc-length technique makes it difficult to define the reference value to be entered in the TEST_RESU command, since these values cannot be imposed. To define the reference values, we looked for the values of :math:`\mathrm{DZ}` that were as close as possible to those listed in the table in [:ref:`§2.2 <§2.2>`] and we reported the values of the control parameter that we had to obtain for the values of :math:`\mathrm{DZ}` in question.