********************************
Elastic Orthotropic Damage Model
********************************

.. code-block:: sierrainput

   BEGIN PARAMETERS FOR MODEL ELASTIC_ORTHOTROPIC_DAMAGE
     #
     # Elastic constants
     #
     YOUNGS MODULUS = <real>
     POISSONS RATIO = <real>
     SHEAR MODULUS  = <real>
     BULK MODULUS   = <real>
     LAMBDA         = <real>
     #
     # Required parameters
     #
     E11    = <real>
     E22    = <real>
     E33    = <real>
     NU12   = <real>
     NU13   = <real>
     NU23   = <real>
     G12    = <real>
     G13    = <real>
     G23    = <real>
     ALPHAD = <real>
     BETAD  = <real>
     GAMMA0 = <real>
     J1     = <real> j1
     J2     = <real> j2
     J3     = <real> j3
     CN11   = <real> cn11
     CN22   = <real> cn22
     CN33   = <real> cn33
     CS12   = <real> cs12
     CS13   = <real> cs13
     CS23   = <real> cs23
     COORDINATE SYSTEM = <string> coordinate_system_name
     #
     # Optional parameters
     #
     ANGLE_1_ABSCISSA = <real>angle_1_abscissa
     ANGLE_2_ABSCISSA = <real>angle_2_abscissa
     ANGLE_3_ABSCISSA = <real>angle_3_abscissa
     ROTATION_AXIS_1  = <real>rotation_axis_1
     ROTATION_AXIS_2  = <real>rotation_axis_2
     ROTATION_AXIS_3  = <real>rotation_axis_3
     ANGLE_1_FUNCTION = <string>angle_1_function_name
     ANGLE_2_FUNCTION = <string>angle_2_function_name
     ANGLE_3_FUNCTION = <string>angle_3_function_name
     E11 FUNCTION    = <string>func_name
     E22 FUNCTION    = <string>func_name
     E33 FUNCTION    = <string>func_name
     NU12 FUNCTION   = <string>func_name
     NU13 FUNCTION   = <string>func_name
     NU23 FUNCTION   = <string>func_name
     G12 FUNCTION    = <string>func_name
     G13 FUNCTION    = <string>func_name
     G23 FUNCTION    = <string>func_name
   END [PARAMETERS FOR MODEL ELASTIC_ORTHOTROPIC_DAMAGE]

The elastic orthotropic damage model is an empirically based constitutive relation that is useful for modeling polymer matrix composite structures.  Refer to SAND2013-7257 for a full description of the material model theory and usage.

The command block for an elastic orthotropic damage material starts with the line:

.. code-block:: sierrainput

   BEGIN PARAMETERS FOR MODEL ELASTIC_ORTHOTROPIC_DAMAGE

and terminates with the line:

.. code-block:: sierrainput

   END [PARAMETERS FOR MODEL ELASTIC_ORTHOTROPIC_DAMAGE]

In the above command block, the required inputs are: two of the five general elastic material constants, directional properties, and the coordinate system. The following is a brief description of each input.

- The density of the material is defined with the ``DENSITY`` command line.
- The Biot's coefficient of the material is defined with the ``BIOTS COEFFICIENT`` command line.
- Any two of the following elastic constants are required:

  -[\textbullet] Young's modulus is defined with the ``YOUNGS MODULUS`` command line.
  -[\textbullet] Poisson's ratio is defined with the ``POISSONS RATIO`` command line.
  -[\textbullet] The bulk modulus is defined with the ``BULK MODULUS`` command line.
  -[\textbullet] The shear modulus is defined with the ``SHEAR MODULUS`` command line.
  -[\textbullet] Lambda is defined with the ``LAMBDA`` command line.

- The directional moduli :math:`E_{11}`, :math:`E_{22}`, and :math:`E_{33}` are defined with the ``E11``, ``E22``, and ``E33`` command lines.
- The directional Poisson's ratios :math:`\nu_{12}`, :math:`\nu_{13}`, and :math:`\nu_{23}` are defined with the ``NU12``, ``NU13``, and ``NU23`` command lines.
- The directional shear moduli :math:`G_{12}`,  :math:`G_{13}`, and  :math:`G_{23}` are defined with the ``G12``, ``G13``, and ``G23`` command lines.
- The specification of the principal material directions begins with the selection of a user specified coordinate system given by the ``COORDINATE SYSTEM`` command line (see below).
- The damage surface evolution terms are given with the ``ALPHAD`` and ``BETAD`` command lines.
- The initial damage threshold is defined with the ``GAMMA0`` command line.
- The directional damage surface coefficients with the ``J1``, ``J2`` and ``J3`` command lines.
- The directional normal crack closure coefficients defined with the ``CN11``, ``CN22`` and ``CN33`` command lines.
- The directional shear crack closure coefficients are defined with the ``CS12``, ``CS13`` and ``CS23`` command lines.
- For material orientation definition instructions see the Sierra/SM User Manual.

.. warning::

   The ``ELASTIC_ORTHOTROPIC_DAMAGE`` model has not been tested in conjunction with the control stiffness implicit solver block.
