FEM: examples, add calculix plate buckling example

src/Mod/Fem/CMakeLists.txt

@@ -44,6 +44,7 @@ SET(FemExamples_SRCS
     femexamples/__init__.py
     femexamples/boxanalysis_static.py
     femexamples/boxanalysis_frequency.py
+    femexamples/buckling_platebuckling.py
     femexamples/ccx_buckling_flexuralbuckling.py
     femexamples/ccx_cantilever_faceload.py
     femexamples/ccx_cantilever_nodeload.py
@@ -78,6 +79,7 @@ SET(FemExampleMeshes_SRCS
     femexamples/meshes/mesh_beamsimple_tetra10.py
     femexamples/meshes/mesh_boxanalysis_tetra10.py
     femexamples/meshes/mesh_boxes_2_vertikal_tetra10.py
+    femexamples/meshes/mesh_buckling_plate_tria6.py
     femexamples/meshes/mesh_canticcx_hexa20.py
     femexamples/meshes/mesh_canticcx_tetra10.py
     femexamples/meshes/mesh_capacitance_two_balls_tetra10.py

src/Mod/Fem/femexamples/buckling_platebuckling.py

@@ -0,0 +1,163 @@
+# ***************************************************************************
+# *   Copyright (c) 2021 Bernd Hahnebach <bernd@bimstatik.org>              *
+# *                                                                         *
+# *   This file is part of the FreeCAD CAx development system.              *
+# *                                                                         *
+# *   This program is free software; you can redistribute it and/or modify  *
+# *   it under the terms of the GNU Lesser General Public License (LGPL)    *
+# *   as published by the Free Software Foundation; either version 2 of     *
+# *   the License, or (at your option) any later version.                   *
+# *   for detail see the LICENCE text file.                                 *
+# *                                                                         *
+# *   This program 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 Library General Public License for more details.                  *
+# *                                                                         *
+# *   You should have received a copy of the GNU Library General Public     *
+# *   License along with this program; if not, write to the Free Software   *
+# *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  *
+# *   USA                                                                   *
+# *                                                                         *
+# ***************************************************************************
+
+# to run the example use:
+"""
+from femexamples.buckling_platebuckling import setup
+setup()
+
+"""
+
+# Forum discussion
+# https://forum.freecadweb.org/viewtopic.php?f=18&t=20217&start=110#p509935
+
+
+import FreeCAD
+import Fem
+import ObjectsFem
+
+
+mesh_name = "Mesh"  # needs to be Mesh to work with unit tests
+
+
+def init_doc(doc=None):
+    if doc is None:
+        doc = FreeCAD.newDocument()
+    return doc
+
+
+def get_information():
+    return {
+        "name": "Plate Buckling",
+        "meshtype": "face",
+        "meshelement": "Tria6",
+        "constraints": ["displacement", "force"],
+        "solvers": ["calculix"],
+        "material": "solid",
+        "equation": "buckling"
+    }
+
+
+def setup(doc=None, solvertype="ccxtools"):
+
+    # init FreeCAD document
+    if doc is None:
+        doc = init_doc()
+
+    # geometric object
+    geom_obj = doc.addObject("Part::Plane", "Plate")
+    geom_obj.Width = 6000
+    geom_obj.Length = 8000
+    doc.recompute()
+    if FreeCAD.GuiUp:
+        geom_obj.ViewObject.Document.activeView().viewAxonometric()
+        geom_obj.ViewObject.Document.activeView().fitAll()
+
+    # analysis
+    analysis = ObjectsFem.makeAnalysis(doc, "Analysis")
+
+    # solver
+    if solvertype == "calculix":
+        solver_obj = ObjectsFem.makeSolverCalculix(doc, "SolverCalculiX")
+    elif solvertype == "ccxtools":
+        solver_obj = ObjectsFem.makeSolverCalculixCcxTools(doc, "CalculiXccxTools")
+        solver_obj.WorkingDir = u""
+    else:
+        FreeCAD.Console.PrintWarning(
+            "Not known or not supported solver type: {}. "
+            "No solver object was created.\n".format(solvertype)
+        )
+    if solvertype == "calculix" or solvertype == "ccxtools":
+        solver_obj.SplitInputWriter = False
+        solver_obj.AnalysisType = "buckling"
+        solver_obj.BucklingFactors = 10
+        solver_obj.GeometricalNonlinearity = "linear"
+        solver_obj.ThermoMechSteadyState = False
+        solver_obj.MatrixSolverType = "default"
+        solver_obj.IterationsControlParameterTimeUse = False
+        solver_obj.BucklingFactors = 1
+    analysis.addObject(solver_obj)
+
+    # shell thickness
+    thickness_obj = ObjectsFem.makeElementGeometry2D(doc, 50, 'Thickness')
+    analysis.addObject(thickness_obj)
+
+    # material
+    material_obj = ObjectsFem.makeMaterialSolid(doc, "Steel")
+    mat = material_obj.Material
+    mat["Name"] = "CalculiX-Steel"
+    mat["YoungsModulus"] = "210000 MPa"
+    mat["PoissonRatio"] = "0.30"
+    material_obj.Material = mat
+    analysis.addObject(material_obj)
+
+    # constraints displacement
+    con_disp_x = ObjectsFem.makeConstraintDisplacement(doc, "ConstraintDisplacement_X")
+    con_disp_x.References = [(geom_obj, "Edge1")]
+    con_disp_x.xFix = True
+    con_disp_x.xFree = False
+    analysis.addObject(con_disp_x)
+
+    con_disp_y = ObjectsFem.makeConstraintDisplacement(doc, "ConstraintDisplacement_Y")
+    con_disp_y.References = [(geom_obj, "Vertex1")]
+    con_disp_y.yFix = True
+    con_disp_y.yFree = False
+    analysis.addObject(con_disp_y)
+
+    con_disp_z = ObjectsFem.makeConstraintDisplacement(doc, "ConstraintDisplacement_Z")
+    con_disp_z.References = [
+        (geom_obj, "Edge1"),
+        (geom_obj, "Edge2"),
+        (geom_obj, "Edge3"),
+        (geom_obj, "Edge4"),
+    ]
+    con_disp_z.zFix = True
+    con_disp_z.zFree = False
+    analysis.addObject(con_disp_z)
+
+    # constraint force
+    con_force = ObjectsFem.makeConstraintForce(doc, "ConstraintForce")
+    con_force.References = [(geom_obj, "Edge3")]
+    con_force.Force = 17162160  # 17'162.16 N
+    con_force.Reversed = True
+    con_force.Direction = (geom_obj, ["Edge2"])
+    analysis.addObject(con_force)
+
+    # mesh
+    from .meshes.mesh_buckling_plate_tria6 import create_nodes, create_elements
+    fem_mesh = Fem.FemMesh()
+    control = create_nodes(fem_mesh)
+    if not control:
+        FreeCAD.Console.PrintError("Error on creating nodes.\n")
+    control = create_elements(fem_mesh)
+    if not control:
+        FreeCAD.Console.PrintError("Error on creating elements.\n")
+    femmesh_obj = analysis.addObject(ObjectsFem.makeMeshGmsh(doc, mesh_name))[0]
+    femmesh_obj.FemMesh = fem_mesh
+    femmesh_obj.Part = geom_obj
+    femmesh_obj.SecondOrderLinear = False
+    femmesh_obj.CharacteristicLengthMax = "300.0 mm"
+    femmesh_obj.ElementDimension = "2D"
+
+    doc.recompute()
+    return doc