Mechanical - Thermal analysis

This examples performs meshing, steady-state and transient thermal analysis of PCB. Objective of this example is to study or examine resulting temperatures caused by the heat developed in chips.

import os
from pathlib import Path

import ansys.mechanical.core as mech
from matplotlib import image as mpimg
from matplotlib import pyplot as plt

/__w/pyansys-workflows/pyansys-workflows/.venv/lib/python3.12/site-packages/trame_vuetify/widgets/vuetify.py:495: SyntaxWarning: invalid escape sequence '\|'
  """

Preparing the environment

This section is only necessary for workflow runs and docs generation. It checks the environment variables to determine which image to use for the mechanical service. If you are running this script outside of a workflow, you can ignore this section.

version = None
if "ANSYS_MECHANICAL_RELEASE" in os.environ:
    image_tag = os.environ["ANSYS_MECHANICAL_RELEASE"]
    version = int(image_tag.replace(".", ""))

Parameters for the script

The following parameters are used to control the script execution. You can modify these parameters to suit your needs.

GRAPHICS_BOOL = False  # Set to True to display the graphics
OUTPUT_DIR = Path(Path(__file__).parent, "outputs")  # Output directory

Start a PyMechanical app

app = mech.App(version=version)
app.update_globals(globals())
print(app)


def display_image(image_name):
    plt.figure(figsize=(16, 9))
    plt.imshow(mpimg.imread(os.path.join(OUTPUT_DIR, image_name)))
    plt.xticks([])
    plt.yticks([])
    plt.axis("off")
    plt.show()

Ansys Mechanical [Ansys Mechanical Enterprise]
Product Version:242
Software build date: 06/03/2024 09:35:09

Configure graphics for image export

ExtAPI.Graphics.Camera.SetSpecificViewOrientation(ViewOrientationType.Iso)
ExtAPI.Graphics.Camera.SetFit()
image_export_format = GraphicsImageExportFormat.PNG
settings_720p = Ansys.Mechanical.Graphics.GraphicsImageExportSettings()
settings_720p.Resolution = GraphicsResolutionType.EnhancedResolution
settings_720p.Background = GraphicsBackgroundType.White
settings_720p.Width = 1280
settings_720p.Height = 720
settings_720p.CurrentGraphicsDisplay = False

Import geometry

Import geometry which is generated with pyansys-geometry

geometry_path = Path(OUTPUT_DIR, "pcb.pmdb")
geometry_import_group = Model.GeometryImportGroup
geometry_import = geometry_import_group.AddGeometryImport()
geometry_import_format = Ansys.Mechanical.DataModel.Enums.GeometryImportPreference.Format.Automatic
geometry_import_preferences = Ansys.ACT.Mechanical.Utilities.GeometryImportPreferences()
geometry_import_preferences.ProcessNamedSelections = True
geometry_import.Import(str(geometry_path), geometry_import_format, geometry_import_preferences)

# Plot geometry
if GRAPHICS_BOOL:
    app.plot()

Static Scene

Interactive Scene

Create named selections

ExtAPI.Application.ActiveUnitSystem = MechanicalUnitSystem.StandardMKS

# Create named selection for all bodies
bodies = Model.Geometry.GetChildren(DataModelObjectCategory.Body, True)
body_ids = [bd.GetGeoBody().Id for bd in bodies]
selection = ExtAPI.SelectionManager.CreateSelectionInfo(SelectionTypeEnum.GeometryEntities)
selection.Ids = body_ids
ns1 = Model.AddNamedSelection()
ns1.Name = "all_bodies"
ns1.Location = selection

# Create named selection for all except substrate
substrate_id = [bd.GetGeoBody().Id for bd in bodies if bd.Name.endswith("substrate")]
except_substrate_id = list(set(body_ids) - set(substrate_id))

selection = ExtAPI.SelectionManager.CreateSelectionInfo(SelectionTypeEnum.GeometryEntities)
selection.Ids = except_substrate_id
ns2 = Model.AddNamedSelection()
ns2.Name = "all_except_board"
ns2.Location = selection

Meshing

mesh = Model.Mesh
mesh.GenerateMesh()

# Export mesh image
ExtAPI.Graphics.Camera.SetFit()
ExtAPI.Graphics.ExportImage(
    os.path.join(OUTPUT_DIR, "mesh.png"), image_export_format, settings_720p
)

# Display the mesh
if GRAPHICS_BOOL:
    display_image("mesh.png")

Analysis

Setup steady state thermal analysis

steady = Model.AddSteadyStateThermalAnalysis()
transient = Model.AddTransientThermalAnalysis()

internal_heat_generation = steady.AddInternalHeatGeneration()
NSall = ExtAPI.DataModel.Project.Model.NamedSelections.GetChildren[
    Ansys.ACT.Automation.Mechanical.NamedSelection
](True)
ic6 = [i for i in NSall if i.Name == "ic-6"][0]
internal_heat_generation.Location = ic6
internal_heat_generation.Magnitude.Output.SetDiscreteValue(0, Quantity(5e7, "W m^-1 m^-1 m^-1"))

all_bodies = [i for i in NSall if i.Name == "all_bodies"][0]
convection = steady.AddConvection()
convection.Location = all_bodies
convection.FilmCoefficient.Output.DiscreteValues = [Quantity("5[W m^-2 C^-1]")]

steady_solution = steady.Solution
temperature_result = steady_solution.AddTemperature()
steady_solution.Solve(True)

# Transient analysis setup
initial_condition = steady_solution.Children[0]
initial_condition.InitialTemperature = InitialTemperatureType.NonUniform
initial_condition.InitialEnvironment = steady

transient_analysis_settings = transient.AnalysisSettings
transient_analysis_settings.StepEndTime = Quantity(200, "sec")

internal_heat_generation2 = transient.AddInternalHeatGeneration()

ic1 = [i for i in NSall if i.Name == "ic-1"][0]
internal_heat_generation2.Location = ic1
internal_heat_generation2.Magnitude.Output.SetDiscreteValue(0, Quantity(5e7, "W m^-1 m^-1 m^-1"))

Add result objects

transient_solution = transient.Solution
transient_temperature_result = transient_solution.AddTemperature()
temperature_probe1 = transient_solution.AddTemperatureProbe()
temperature_probe1.GeometryLocation = ic6
temperature_probe2 = transient_solution.AddTemperatureProbe()
temperature_probe2.GeometryLocation = ic1

Solve

transient_solution.Solve(True)

Save files and close Mechanical

Mechanical file (mechdb) contains results for each analysis

app.save(os.path.join(OUTPUT_DIR, "pcb.mechdb"))
project_directory = ExtAPI.DataModel.Project.ProjectDirectory
app.exit()