cohesive_extrinsic (2D)
'''''''''''''''''''''''

:Sources:

.. collapse:: cohesive_extrinsic.cc (click to expand)

.. literalinclude:: examples/c++/solid_mechanics_cohesive_model/cohesive_extrinsic/cohesive_extrinsic.cc
:language: c++
:lines: 20-

.. collapse:: material.dat (click to expand)

.. literalinclude:: examples/c++/solid_mechanics_cohesive_model/cohesive_extrinsic/material.dat
:language: text

:Location:

``examples/c++/solid_mechanics_cohesive_model/`` `cohesive_extrinsic <https://gitlab.com/akantu/akantu/-/blob/master/examples/c++/solid_mechanics_cohesive_model/cohesive_extrinsic/>`_


In ``cohesive_extrinsic``, an example of extrinsic cohesive elements is shown.
An extrinsic simulation is initialized by setting ``_is_extrinsic`` argument of ``model.initFull`` to ``true``::

model.initFull(_analysis_method = _explicit_lumped_mass, _is_extrinsic = true);

Cohesive elements are inserted during the simulation but at a location restricted with::

CohesiveElementInserter & inserter = model.getElementInserter();
inserter.setLimit(_y, 0.30, 0.20);
model.updateAutomaticInsertion();

During the simulation, stress has to be checked in order to insert cohesive elements where the stress criterion is reached. This check is performed by calling the method ``checkCohesiveStress`` before each step resolution::

model.checkCohesiveStress();
model.solveStep();

For this specific example, a displacement is imposed based on the elements location. The corresponding displacements is shown in :numref:`fig-ex-cohesive-ext`.

.. _fig-ex-cohesive-ext:
.. figure:: examples/c++/solid_mechanics_cohesive_model/cohesive_extrinsic/images/cohesive_extrinsic.gif
:align: center
:width: 90%

Displacement in the y direction for the cohesive_extrinsic example.