# 15.2. Elastic Orthotropic Damage Model

    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:

    BEGIN PARAMETERS FOR MODEL ELASTIC_ORTHOTROPIC_DAMAGE

and terminates with the line:

    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 \(E_{11}\), \(E_{22}\), and \(E_{33}\) are defined with the `E11`, `E22`, and `E33` command lines.

- The directional Poisson’s ratios \(\nu_{12}\), \(\nu_{13}\), and \(\nu_{23}\) are defined with the `NU12`, `NU13`, and `NU23` command lines.

- The directional shear moduli \(G_{12}\), \(G_{13}\), and \(G_{23}\) 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.