Fix Field Indexer and get_element_indices for layered solids and add …

…example of a thermal analysis (#512)

* Fix Field Indexer by distinguish between fields with data pointers and without
Add draft of an example for a thermal analysis

* fix `select_indices` for layered solid elements

* verify `get_selected_indices` for all types of layered elements

examples/013_thermal_example.py

@@ -0,0 +1,128 @@
+# Copyright (C) 2023 - 2024 ANSYS, Inc. and/or its affiliates.
+# SPDX-License-Identifier: MIT
+#
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+"""
+.. _thermal_example:
+
+Thermal analysis
+----------------
+
+PyDPF Composites can also be used to post-process thermal analyses.
+In this case, the simulation is a two-step analysis where the results of
+a thermal analysis are an input of the structural analysis. So, the RST
+contains temperature and structural results.
+The example mimics a PCB which was modeled with Ansys Composites PrePost (ACP).
+where the solid model feature of ACP is used to generate the volume mesh.
+
+In detail, the example shows how to extract the temperatures for a specific ply,
+and a specific material.
+
+.. note::
+
+    When using a Workbench project,
+    use the :func:`.get_composite_files_from_workbench_result_folder`
+    method to obtain the input files.
+
+"""
+
+# %%
+# Set up analysis
+# ~~~~~~~~~~~~~~~
+# Setting up the analysis consists of loading the required modules, connecting to the
+# DPF server, and retrieving the example files.
+#
+import ansys.dpf.core as dpf
+import numpy as np
+
+from ansys.dpf.composites.composite_model import CompositeModel
+from ansys.dpf.composites.constants import TEMPERATURE_COMPONENT
+from ansys.dpf.composites.example_helper import get_continuous_fiber_example_files
+from ansys.dpf.composites.layup_info import get_all_analysis_ply_names
+from ansys.dpf.composites.ply_wise_data import SpotReductionStrategy, get_ply_wise_data
+from ansys.dpf.composites.select_indices import get_selected_indices_by_dpf_material_ids
+from ansys.dpf.composites.server_helpers import connect_to_or_start_server
+
+server = connect_to_or_start_server()
+composite_files = get_continuous_fiber_example_files(server, "thermal_solid")
+
+# %%
+# Initialize the model
+# ~~~~~~~~~~~~~~~~~~~~
+# The composite model is initialized with the composite files and the server.
+# It provides access to the mesh, results, lay-up and materials
+composite_model = CompositeModel(composite_files, server)
+
+# %%
+# Get Results - Temperatures
+# ~~~~~~~~~~~~~~~~~~~~~~~~~~
+# The temperatures are stored under structural_temperature
+temp_op = composite_model.core_model.results.structural_temperature()
+temperatures_fc = temp_op.outputs.fields_container()
+
+# %%
+# Ply-wise results
+# ~~~~~~~~~~~~~~~~
+# Ply-wise results can be easily extracted using the function
+# :func:`.get_ply_wise_data` and by passing the ply name.
+
+all_ply_names = get_all_analysis_ply_names(composite_model.get_mesh())
+print(all_ply_names)
+
+nodal_values = get_ply_wise_data(
+    field=temperatures_fc,
+    ply_name="P1L1__ModelingPly.8",
+    mesh=composite_model.get_mesh(),
+    component=TEMPERATURE_COMPONENT,
+    spot_reduction_strategy=SpotReductionStrategy.MAX,
+    requested_location=dpf.locations.nodal,
+)
+
+composite_model.get_mesh().plot(nodal_values)
+
+# %%
+# Material-wise results
+# ~~~~~~~~~~~~~~~~~~~~~
+# It is also possible to filter the results by material.
+# In this example the element-wise maximum temperature
+# is extracted for the material `Honeycomb Aluminum Alloy`.
+print(composite_model.material_names)
+material_id = composite_model.material_names["Honeycomb Aluminum Alloy"]
+
+# get the last result field
+temperatures_field = temperatures_fc[-1]
+
+material_result_field = dpf.field.Field(location=dpf.locations.elemental, nature=dpf.natures.scalar)
+# performance optimization: use a local field instead of a field which is pushed to the server
+with material_result_field.as_local_field() as local_result_field:
+    element_ids = temperatures_field.scoping.ids
+
+    for element_id in element_ids:
+        element_info = composite_model.get_element_info(element_id)
+        assert element_info is not None
+        if material_id in element_info.dpf_material_ids:
+            temp_data = temperatures_field.get_entity_data_by_id(element_id)
+            selected_indices = get_selected_indices_by_dpf_material_ids(element_info, [material_id])
+
+            value = np.max(temp_data[selected_indices])
+            local_result_field.append([value], element_id)
+
+composite_model.get_mesh().plot(material_result_field)