.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "examples/ex17_torsion-gif.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download_examples_ex17_torsion-gif.py>`
        to download the full example code.

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_examples_ex17_torsion-gif.py:


Animated torsional-shear loading
--------------------------------

.. topic:: Save an animation of a custom boundary condition.

   * assign non-homogeneous displacements to a boundary condition

   * create an animation

   * export a GIF-movie

   * evaluate the reaction moment on a boundary condition

This example demonstrates how to create a :class:`~felupe.Boundary` for torsional
loading. This is somewhat more complicated than a simple boundary condition with
identical mesh-point values because the values of the mesh-points are different.
However, this is not a problem. FElupe supports arrays to be passed as the ``value``-
argument of a :class:`~felupe.Boundary`. This is even possible in a
:class:`~felupe.Step` with the ``ramp``-argument.

.. GENERATED FROM PYTHON SOURCE LINES 22-50

.. code-block:: Python


    import matplotlib.pyplot as plt
    import numpy as np

    import felupe as fem

    mesh = fem.mesh.Triangle(n=3).expand(n=6)
    field = fem.FieldContainer([fem.Field(fem.RegionHexahedron(mesh), dim=3)])

    boundaries = {
        "bottom": fem.Boundary(field[0], fz=0),
        "top": fem.Boundary(field[0], fz=1),
    }
    solid = fem.SolidBody(umat=fem.NeoHookeCompressible(mu=1, lmbda=2), field=field)

    angles_deg = fem.math.linsteps([0, -30, 0], num=5)[:-1]
    move = []
    for phi in angles_deg:
        top = mesh.points[boundaries["top"].points]
        top_rotated = fem.math.rotate_points(
            points=top,
            angle_deg=phi,
            axis=2,
            center=[0, 0, 1],
        )
        move.append(top_rotated - top)









.. GENERATED FROM PYTHON SOURCE LINES 52-56

The reaction moment on the centerpoint of the right end face is tracked by a custom
:class:`~felupe.Plugin` during :class:`~felupe.Job` evaluation after each completed
substep. The animation of the deformation is written to a GIF-file by
:class:`~felupe.AnimationWriterPlugin`.

.. GENERATED FROM PYTHON SOURCE LINES 56-79

.. code-block:: Python

    class ReactionMoment(fem.Plugin):
        def __init__(self):
            self.values = []

        def after_substep(self, context, state):
            # evaluate the reaction moment at the centerpoint of the right end face
            forces = context.substep.fun
            M = fem.tools.moment(field, forces, boundaries["top"], centerpoint=[0, 0, 1])
            self.values.append(M)


    animation = fem.AnimationWriterPlugin(
        items=[field],
        filename="result.gif",
        name="Principal Values of Logarithmic Strain",
        component=0,  # max. principal value of logarithmic strain
        reset_camera=False,
        clim=[0, 0.2],
    )
    moment = ReactionMoment()
    step = fem.Step(items=[solid], ramp={boundaries["top"]: move}, boundaries=boundaries)
    job = fem.Job(steps=[step], plugins=[animation, moment]).evaluate()





.. image-sg:: /examples/images/sphx_glr_ex17_torsion-gif_001.gif
   :alt: ex17 torsion gif
   :srcset: /examples/images/sphx_glr_ex17_torsion-gif_001.gif
   :class: sphx-glr-single-img







.. GENERATED FROM PYTHON SOURCE LINES 80-81

Finally, let's plot the reaction moment vs. torsion angle curve.

.. GENERATED FROM PYTHON SOURCE LINES 81-85

.. code-block:: Python

    fig, ax = plt.subplots()
    ax.plot(abs(angles_deg), abs(np.array(moment.values)[:, 2]), "o-")
    ax.set_xlabel(r"Torsion Angle $|\phi_3|$ in deg $\rightarrow$")
    ax.set_ylabel(r"Torsion Moment $|M_3|$ in Nmm $\rightarrow$")



.. image-sg:: /examples/images/sphx_glr_ex17_torsion-gif_002.png
   :alt: ex17 torsion gif
   :srcset: /examples/images/sphx_glr_ex17_torsion-gif_002.png
   :class: sphx-glr-single-img






.. rst-class:: sphx-glr-timing

   **Total running time of the script:** (0 minutes 3.664 seconds)


.. _sphx_glr_download_examples_ex17_torsion-gif.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: sphx-glr-download sphx-glr-download-jupyter

      :download:`Download Jupyter notebook: ex17_torsion-gif.ipynb <ex17_torsion-gif.ipynb>`

    .. container:: sphx-glr-download sphx-glr-download-python

      :download:`Download Python source code: ex17_torsion-gif.py <ex17_torsion-gif.py>`

    .. container:: sphx-glr-download sphx-glr-download-zip

      :download:`Download zipped: ex17_torsion-gif.zip <ex17_torsion-gif.zip>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_