Add beam element in skin extraction (#778)

* Add beam element in skin extraction

Author: janvonrickenbach

src/ansys/dpf/post/selection.py

@@ -421,6 +421,9 @@ def select_skin(
             on the expanded mesh.
         """
         skin_operator = operators.mesh.skin(server=self._server)
+        if self._server.meet_version("9.1"):
+            # add_beam argument is not available in versions prior to 9.0
+            skin_operator.inputs.add_beam(True)
         self._selection.add_operator(skin_operator)
 
         initial_mesh_fwd_op = operators.utility.forward(server=self._server)

tests/conftest.py

@@ -196,6 +196,13 @@ def average_per_body_complex_multi_body():
     )
 
 
+@pytest.fixture()
+def beam_example():
+    return _download_file(
+        "result_files/beams", "post_beam_result_01.rst", True, None, False
+    )
+
+
 @dataclasses.dataclass
 class ReferenceCsvFilesNodal:
     # reference result with all bodies combined

tests/test_simulation.py

@@ -1,5 +1,6 @@
 import csv
 import dataclasses
+from itertools import groupby
 import os.path
 import pathlib
 from typing import Optional, Union
@@ -4618,3 +4619,33 @@ def test_build_selection(
             assert len(scoping_from_selection.ids) == 36
         else:
             assert set(scoping_from_selection.ids) == set(scoping.ids)
+
+
+def test_beam_results_on_skin(beam_example):
+    simulation: StaticMechanicalSimulation = post.load_simulation(
+        data_sources=beam_example,
+        simulation_type=AvailableSimulationTypes.static_mechanical,
+    )
+    if not SERVERS_VERSION_GREATER_THAN_OR_EQUAL_TO_9_1:
+        # Add beams on skin not supported before 9.1
+        return
+
+    res = simulation.displacement(skin=True, norm=True)
+
+    element_type_array = res._fc[0].meshed_region.elements.element_types_field.data
+    element_count_dict = {
+        key: sum(1 for _ in value) for key, value in groupby(sorted(element_type_array))
+    }
+
+    unit_converter = dpf.operators.math.unit_convert(
+        unit_name=2,  # NMM unit system
+    )
+
+    unit_converter.inputs.entity_to_convert(res._fc[0])
+    converted_field = unit_converter.eval()
+
+    assert element_types.Line2.value in element_count_dict.keys()
+
+    assert element_count_dict[element_types.Line2.value] == 40
+
+    assert converted_field.max().data[0] == pytest.approx(190, 1e-2)