.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "examples/05_workflows/cad_to_fea_tet_mesh.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

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

        :ref:`Go to the end <sphx_glr_download_examples_05_workflows_cad_to_fea_tet_mesh.py>`
        to download the full example code.

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

.. _sphx_glr_examples_05_workflows_cad_to_fea_tet_mesh.py:


CAD shape to tetrahedral FEA mesh
=================================

Drive a CAD shape through gmsh to obtain a tetrahedral mesh suitable
for finite-element analysis, then bring the volumetric result back
into PyVista as an :class:`pyvista.UnstructuredGrid`.

This imports a real STEP part, the NIST AM Bench 2022 LPBF bridge
specimen (public domain, https://doi.org/10.18434/mds2-2607),
directly into gmsh via ``gmsh.model.occ.importShapes``, the canonical
way to move from CAD to FEA, and meshes the volume tetrahedrally.

.. GENERATED FROM PYTHON SOURCE LINES 16-24

.. code-block:: Python


    import gmsh
    import pandas as pd
    import pyvista as pv

    import pyvista_cad
    from pyvista_cad.examples import downloads








.. GENERATED FROM PYTHON SOURCE LINES 25-26

Import the real STEP into gmsh's OCC kernel and mesh the volume.

.. GENERATED FROM PYTHON SOURCE LINES 26-46

.. code-block:: Python


    gmsh.initialize()
    try:
        gmsh.model.add('part_fea')
        gmsh.model.occ.importShapes(downloads.step_part_path())
        gmsh.model.occ.synchronize()

        gmsh.option.setNumber('Mesh.MeshSizeMax', 2.0)
        gmsh.option.setNumber('Mesh.MeshSizeMin', 0.5)
        gmsh.model.mesh.generate(3)
        grid = pyvista_cad.from_gmsh('part_fea')
    finally:
        gmsh.finalize()

    # gmsh returns a mixed grid (vertex, line, triangle, tet). For a
    # volumetric FEA mesh we only keep VTK_TETRA (cell type 10).
    VTK_TETRA = 10
    grid = grid.extract_cells(grid.celltypes == VTK_TETRA)
    grid






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    </style><pre class='pv-text-repr-fallback'>UnstructuredGrid (0x7f6fa8111120)
      N Cells:    6470
      N Points:   2041
      X Bounds:   0.000e+00, 7.500e+01
      Y Bounds:   -2.446e-13, 5.000e+00
      Z Bounds:   0.000e+00, 1.225e+01
      N Arrays:   3</pre><div class='pv-wrap' style='display:none'><div class='pv-header'><span class='pv-logo'><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32">
      <defs>
        <linearGradient id="pv-ug-g1" x1="0" y1="0" x2="1" y2="1">
          <stop offset="0%" stop-color="#ffd040"/>
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      </defs>
      <polygon points="3,10 8,5 14,7 13,13 6,14" fill="#376fa0" opacity="0.9"/>
      <polygon points="14,7 22,4 20,12" fill="url(#pv-ug-g1)" opacity="0.85"/>
      <polygon points="22,4 29,9 27,17 20,12" fill="#1a4a70" opacity="0.85"/>
      <polygon points="13,13 20,12 16,20" fill="#ffd040" opacity="0.8"/>
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        <polygon points="22,4 29,9 27,17 20,12"/>
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        <polygon points="20,12 27,17 26,25 18,28 16,20"/>
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        <circle cx="29" cy="9" r="0.9"/>
        <circle cx="13" cy="13" r="0.9"/>
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        <circle cx="27" cy="17" r="0.9"/>
        <circle cx="16" cy="20" r="0.9"/>
        <circle cx="4" cy="20" r="0.9"/>
        <circle cx="10" cy="24" r="0.9"/>
        <circle cx="26" cy="25" r="0.9"/>
        <circle cx="18" cy="28" r="0.9"/>
      </g>
    </svg>
    </span><div class='pv-header-text'><div class='pv-obj-type'>UnstructuredGrid <span class='pv-header-badge'>2,041 points</span> <span class='pv-header-badge'>6,470 cells</span> <span class='pv-header-badge'>377 KiB</span></div></div><span class='pv-brand-logo'><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 90 24">
      <text x="0" y="18" font-family="system-ui,-apple-system,sans-serif" font-size="18" font-weight="700" font-style="italic" letter-spacing="-0.5">
        <tspan fill="#3776AB" opacity="0.7">P</tspan><tspan fill="#FFD43B" opacity="0.7">y</tspan><tspan fill="#008c9e">Vista</tspan>
      </text>
    </svg>
    </span></div><div class='pv-metadata'><div class='pv-meta-row pv-copyable'><span class='pv-meta-row-label'>Bounds</span><button class='pv-copy-btn' title='Copy to clipboard' data-copy='(0.0, 75.00000000000003, -2.445960101127298e-13, 5.000000000000262, 0.0, 12.25)' onclick="navigator.clipboard.writeText(this.dataset.copy)">⧉</button><span class='pv-meta-entry'><span class='pv-meta-label'>X</span> [0.000e+00, 7.500e+01]</span><span class='pv-meta-entry'><span class='pv-meta-label'>Y</span> [-2.446e-13, 5.000e+00]</span><span class='pv-meta-entry'><span class='pv-meta-label'>Z</span> [0.000e+00, 1.225e+01]</span></div></div><ul class='pv-sections'><li class='pv-section-item'><input id='section-da7337cd-96b8-47d5-86ed-9b83be2f355d' class='pv-section-summary-in' type='checkbox' checked /><label for='section-da7337cd-96b8-47d5-86ed-9b83be2f355d' class='pv-section-summary' title='Expand/collapse section'>Point Data: <span>(1)</span></label><div class='pv-section-inline-details'></div><div class='pv-section-details'><ul class='pv-var-list'><li class='pv-var-item'><div class='pv-var-name'><span>vtkOriginalPointIds</span><button class='pv-copy-btn' title='Copy to clipboard' data-copy='vtkOriginalPointIds' onclick="navigator.clipboard.writeText(this.dataset.copy)">⧉</button></div><div class='pv-var-dims'>scalar</div><div class='pv-var-dtype'>int64</div><div class='pv-var-range'>[0.000e+00, 2.040e+03]</div><div class='pv-var-badges'></div></li></ul></div></li><li class='pv-section-item'><input id='section-93a3bb12-68c4-4cdd-9463-5520d721492c' class='pv-section-summary-in' type='checkbox' checked /><label for='section-93a3bb12-68c4-4cdd-9463-5520d721492c' class='pv-section-summary' title='Expand/collapse section'>Cell Data: <span>(1)</span></label><div class='pv-section-inline-details'></div><div class='pv-section-details'><ul class='pv-var-list'><li class='pv-var-item'><div class='pv-var-name'><span>vtkOriginalCellIds</span><button class='pv-copy-btn' title='Copy to clipboard' data-copy='vtkOriginalCellIds' onclick="navigator.clipboard.writeText(this.dataset.copy)">⧉</button></div><div class='pv-var-dims'>scalar</div><div class='pv-var-dtype'>int64</div><div class='pv-var-range'>[4.456e+03, 1.092e+04]</div><div class='pv-var-badges'></div></li></ul></div></li><li class='pv-section-item'><input id='section-11cdbf77-7378-4cd1-bca9-57dc85fd48a8' class='pv-section-summary-in' type='checkbox' checked /><label for='section-11cdbf77-7378-4cd1-bca9-57dc85fd48a8' class='pv-section-summary' title='Expand/collapse section'>Field Data: <span>(1)</span></label><div class='pv-section-inline-details'></div><div class='pv-section-details'><ul class='pv-var-list'><li class='pv-var-item'><div class='pv-var-name'><span>cad.source_format</span><button class='pv-copy-btn' title='Copy to clipboard' data-copy='cad.source_format' onclick="navigator.clipboard.writeText(this.dataset.copy)">⧉</button></div><div class='pv-var-dims'>(1,)</div><div class='pv-var-dtype'>&lt;U4</div><div class='pv-var-range'></div><div class='pv-var-badges'></div></li></ul></div></li></ul></div></div>
    </div>
    <br />
    <br />

.. GENERATED FROM PYTHON SOURCE LINES 47-48

Quality check: a healthy tet mesh has no zero-volume elements.

.. GENERATED FROM PYTHON SOURCE LINES 48-58

.. code-block:: Python


    vols = grid.compute_cell_sizes(length=False, area=False, volume=True)['Volume']

    pd.DataFrame(
        {
            'metric': ['min', 'mean', 'max'],
            'tet_volume': [vols.min(), vols.mean(), vols.max()],
        }
    )






.. raw:: html

    <div class="output_subarea output_html rendered_html output_result">
    <div>
    <style scoped>
        .dataframe tbody tr th:only-of-type {
            vertical-align: middle;
        }

        .dataframe tbody tr th {
            vertical-align: top;
        }

        .dataframe thead th {
            text-align: right;
        }
    </style>
    <table border="1" class="dataframe">
      <thead>
        <tr style="text-align: right;">
          <th></th>
          <th>metric</th>
          <th>tet_volume</th>
        </tr>
      </thead>
      <tbody>
        <tr>
          <th>0</th>
          <td>min</td>
          <td>0.005826</td>
        </tr>
        <tr>
          <th>1</th>
          <td>mean</td>
          <td>0.551671</td>
        </tr>
        <tr>
          <th>2</th>
          <td>max</td>
          <td>3.264683</td>
        </tr>
      </tbody>
    </table>
    </div>
    </div>
    <br />
    <br />

.. GENERATED FROM PYTHON SOURCE LINES 59-60

Slice through the part to expose the tet interior.

.. GENERATED FROM PYTHON SOURCE LINES 60-69

.. code-block:: Python


    bnds = grid.bounds
    clip = grid.clip(normal='x', crinkle=True)
    clip['Z'] = clip.points[:, 2]

    pl = pv.Plotter()
    pl.add_mesh(grid, color='lightgray', opacity=0.15)
    pl.add_mesh(clip, scalars='Z', cmap='inferno', show_edges=True, edge_color='black')
    pl.show()







.. tab-set::



   .. tab-item:: Static Scene



            
     .. image-sg:: /examples/05_workflows/images/sphx_glr_cad_to_fea_tet_mesh_001.png
        :alt: cad to fea tet mesh
        :srcset: /examples/05_workflows/images/sphx_glr_cad_to_fea_tet_mesh_001.png
        :class: sphx-glr-single-img
     


   .. tab-item:: Interactive Scene



       .. offlineviewer:: /home/runner/work/pyvista-cad/pyvista-cad/doc/examples/05_workflows/images/sphx_glr_cad_to_fea_tet_mesh_001.vtksz







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

   **Total running time of the script:** (0 minutes 0.884 seconds)


.. _sphx_glr_download_examples_05_workflows_cad_to_fea_tet_mesh.py:

.. only:: html

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

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

      :download:`Download Jupyter notebook: cad_to_fea_tet_mesh.ipynb <cad_to_fea_tet_mesh.ipynb>`

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

      :download:`Download Python source code: cad_to_fea_tet_mesh.py <cad_to_fea_tet_mesh.py>`

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

      :download:`Download zipped: cad_to_fea_tet_mesh.zip <cad_to_fea_tet_mesh.zip>`