Merge pull request #20011 from FEA-eng/fem_example_rigid_body

FEM: Add ccx rigid body constraint example

src/Mod/Fem/CMakeLists.txt

@@ -66,6 +66,7 @@ SET(FemExamples_SRCS
     femexamples/ccx_cantilever_faceload.py
     femexamples/ccx_cantilever_nodeload.py
     femexamples/ccx_cantilever_prescribeddisplacement.py
+    femexamples/ccx_rigid_body.py
     femexamples/constraint_centrif.py
     femexamples/constraint_contact_shell_shell.py
     femexamples/constraint_contact_solid_solid.py

src/Mod/Fem/femexamples/ccx_rigid_body.py

@@ -0,0 +1,151 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
+
+# ***************************************************************************
+# *   Copyright (c) 2025 Jakub Michalski <jakub.j.michalski[at]gmail.com>         *
+# *                                                                         *
+# *   This file is part of FreeCAD.                                         *
+# *                                                                         *
+# *   FreeCAD is free software: you can redistribute it and/or modify it    *
+# *   under the terms of the GNU Lesser General Public License as           *
+# *   published by the Free Software Foundation, either version 2.1 of the  *
+# *   License, or (at your option) any later version.                       *
+# *                                                                         *
+# *   FreeCAD is distributed in the hope that it will be useful, but        *
+# *   WITHOUT ANY WARRANTY; without even the implied warranty of            *
+# *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU      *
+# *   Lesser General Public License for more details.                       *
+# *                                                                         *
+# *   You should have received a copy of the GNU Lesser General Public      *
+# *   License along with FreeCAD. If not, see                               *
+# *   <https://www.gnu.org/licenses/>.                                      *
+# *                                                                         *
+# ***************************************************************************
+
+import FreeCAD as App
+
+import Part
+import Fem
+import ObjectsFem
+
+from . import manager
+from .manager import get_meshname
+from .manager import init_doc
+
+
+def get_information():
+    return {
+        "name": "Rigid body constraint",
+        "meshtype": "solid",
+        "meshelement": "Tet10",
+        "constraints": ["fixed", "rigid body"],
+        "solvers": ["ccxtools"],
+        "material": "solid",
+        "equations": ["mechanical"],
+    }
+
+
+def get_explanation(header=""):
+    return (
+        header
+        + """
+
+To run the example from Python console use:
+from femexamples.ccx_rigid_body import setup
+setup()
+
+
+Analytical solution - max xz stress = 2.547 MPa = 2.547e6 Pa
+
+"""
+    )
+
+
+def setup(doc=None, solvertype="ccxtools"):
+
+    # init FreeCAD document
+    if doc is None:
+        doc = init_doc()
+
+    # explanation object
+    # just keep the following line and change text string in get_explanation method
+    manager.add_explanation_obj(doc, get_explanation(manager.get_header(get_information())))
+
+    # geometric object
+    ellipse = doc.addObject("Part::Ellipse", "Ellipse")
+    ellipse.MajorRadius = "100,00 mm"
+    ellipse.MinorRadius = "50,00 mm"
+    ellipse.Angle1 = "0,00 °"
+    ellipse.Angle2 = "360,00 °"
+    ellipse.Placement = App.Placement(
+        App.Vector(0.00, 0.00, 0.00), App.Rotation(App.Vector(0.00, 0.00, 1.00), 0.00)
+    )
+    extrude = doc.addObject("Part::Extrusion", "Extrude")
+    extrude.Base = ellipse
+    extrude.LengthFwd = 1000
+    extrude.Solid = True
+    ellipse.Visibility = False
+    doc.recompute()
+    if App.GuiUp:
+        extrude.ViewObject.Document.activeView().viewAxonometric()
+        extrude.ViewObject.Document.activeView().fitAll()
+
+    # analysis
+    analysis = ObjectsFem.makeAnalysis(doc, "Analysis")
+
+    # solver,
+    if solvertype == "ccxtools":
+        solver_obj = ObjectsFem.makeSolverCalculiXCcxTools(doc, "CalculiXCcxTools")
+        solver_obj.WorkingDir = ""
+    else:
+        FreeCAD.Console.PrintWarning(
+            "Unknown or unsupported solver type: {}. "
+            "No solver object was created.\n".format(solvertype)
+        )
+    if solvertype == "ccxtools":
+        solver_obj.SplitInputWriter = False
+        solver_obj.AnalysisType = "static"
+    analysis.addObject(solver_obj)
+
+    # material
+    material_obj = ObjectsFem.makeMaterialSolid(doc, "MechanicalMaterial")
+    mat = material_obj.Material
+    mat["Name"] = "CalculiX-Steel"
+    mat["YoungsModulus"] = "210000 MPa"
+    mat["PoissonRatio"] = "0.30"
+    material_obj.Material = mat
+    material_obj.References = [(extrude, "Solid1")]
+    analysis.addObject(material_obj)
+
+    # constraint fixed
+    con_fixed = ObjectsFem.makeConstraintFixed(doc, "ConstraintFixed")
+    con_fixed.References = [(extrude, "Face2")]
+    analysis.addObject(con_fixed)
+
+    # constraint rigid body
+    con_rb = ObjectsFem.makeConstraintRigidBody(doc, "ConstraintRigidBody")
+    con_rb.References = [(extrude, "Face3")]
+    con_rb.ReferenceNode = App.Vector(0.000000, 0.000000, 1000.000000)
+    con_rb.Rotation = App.Rotation(App.Vector(0.000000, 0.000000, 1.000000), Radian=0.000000)
+    con_rb.MomentZ = "1,00 kJ"
+    con_rb.RotationalModeZ = "Load"
+    analysis.addObject(con_rb)
+
+    # mesh
+    femmesh_obj = analysis.addObject(ObjectsFem.makeMeshGmsh(doc, get_meshname()))[0]
+    femmesh_obj.Shape = extrude
+    femmesh_obj.ElementOrder = "2nd"
+    femmesh_obj.CharacteristicLengthMax = "15 mm"
+    femmesh_obj.ViewObject.Visibility = False
+
+    # generate the mesh
+    from femmesh import gmshtools
+
+    gmsh_mesh = gmshtools.GmshTools(femmesh_obj, analysis)
+    try:
+        error = gmsh_mesh.create_mesh()
+    except Exception:
+        error = sys.exc_info()[1]
+        FreeCAD.Console.PrintError(f"Unexpected error when creating mesh: {error}\n")
+
+    doc.recompute()
+    return doc