Materials
=========

Material properties are set with :meth:`femorph_solver.Model.mp`, the direct
analogue of MAPDL's ``MP`` command.  Every property is a scalar
attached to a material id; an element references its material by
stamping a ``MAT`` id with :meth:`~femorph_solver.Model.mat` before
:meth:`~femorph_solver.Model.e` creates it.

MP
--

.. code-block:: python

    m = femorph_solver.Model()
    m.mp("EX", 1, 2.1e11)       # Young's modulus (Pa)
    m.mp("PRXY", 1, 0.30)       # Poisson ratio
    m.mp("DENS", 1, 7850.0)     # density (kg/m^3)

The first argument is the property name, the second is the material
id, the third is the scalar value.  Units are whatever's consistent
across ``EX``, the element geometry, and any forces — femorph-solver does not
track units.

Supported properties
--------------------

The :class:`femorph_solver.MaterialProperty` enum enumerates every property
name femorph-solver's element kernels currently look up.  Accepting the enum
member or the raw string is equivalent:

.. list-table::
    :widths: 15 55 30
    :header-rows: 1

    * - Token
      - Meaning
      - Used by
    * - ``EX``
      - Young's modulus
      - All solids, beams, shells, plane, truss.
    * - ``PRXY``
      - Poisson's ratio (isotropic)
      - All solids, beams, shells, plane.
    * - ``DENS``
      - Mass density
      - Every element that contributes to :math:`M`.
    * - ``GXY``
      - Transverse shear modulus
      - Reserved for future shell / beam transverse-shear paths.
    * - ``ALPX``
      - Thermal expansion coefficient
      - Reserved for future thermal-strain coupling.

.. code-block:: python

    from femorph_solver import MaterialProperty as MP

    m.mp(MP.EX, 1, 2.1e11)      # enum-typed — identical to "EX"

Multiple materials
------------------

Assign different materials to different element groups by alternating
the :meth:`~femorph_solver.Model.mat` stamp::

    m.mat(1)                         # MAT,1
    m.e(1, 2, 3, 4, 5, 6, 7, 8)      # uses material 1

    m.mat(2)                         # MAT,2
    m.e(9, 10, 11, 12, 13, 14, 15, 16)   # uses material 2

    m.mp("EX", 1, 2.1e11)            # material 1: steel-ish
    m.mp("PRXY", 1, 0.30)
    m.mp("DENS", 1, 7850.0)

    m.mp("EX", 2, 7.0e10)            # material 2: aluminium-ish
    m.mp("PRXY", 2, 0.33)
    m.mp("DENS", 2, 2700.0)

When a CDB is loaded, each element arrives with a material id already
stamped; there's no additional registration step beyond calling
:meth:`mp` for every ``mat_id`` that appears on the grid.

Introspection
-------------

The current material table is available as :attr:`Model.materials`::

    m.materials
    # {1: {'EX': 2.1e11, 'PRXY': 0.3, 'DENS': 7850.0},
    #  2: {'EX': 7.0e10, 'PRXY': 0.33, 'DENS': 2700.0}}

Element kernels read the matching dict directly, so any additional
scalar you stash under a known property name is visible to them —
this is the extension path for per-element-class switches (e.g.
``_SOLID185_FORMULATION``; see the :doc:`SOLID185 reference
<elements/solid185>`).

Limitations (today)
-------------------

- **Linear isotropic only.**  Orthotropic / anisotropic tensors, rate
  dependence, plasticity, temperature-dependent curves are not yet
  implemented.
- **Scalar per id.**  Tensor-valued ``DMATRIX`` / ``ANEL`` MAPDL
  blocks aren't round-tripped yet; they're parsed on CDB load but
  ignored during assembly.

See also
--------

- :doc:`real-constants` — per-element-type geometric data (``R`` command).
- :doc:`/user-guide/pre-processing/elements/index` — which properties
  each element class reads.