src/Mod/Fem/femexamples/equation_deformation_spring_elmer.py

# ***************************************************************************
# *   Copyright (c) 2023 Uwe Stöhr <uwestoehr@lyx.org>                      *
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# *   This file is part of the FreeCAD CAx development system.              *
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import sys
import FreeCAD
from FreeCAD import Vector

import ObjectsFem
import Part
import Sketcher

from . import manager
from .manager import get_meshname
from .manager import init_doc


def get_information():
    return {
        "name": "Deformation (nonlinear elasticity) - Elmer",
        "meshtype": "solid",
        "meshelement": "Tet10",
        "constraints": ["displacement", "spring"],
        "solvers": ["elmer"],
        "material": "solid",
        "equations": ["deformation"],
    }


def get_explanation(header=""):
    return (
        header
        + """

To run the example from Python console use:
from femexamples.equation_deformation_spring_elmer import setup
setup()

Deformation equation - Elmer solver

"""
    )


def setup(doc=None, solvertype="elmer"):

    # 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 objects

    # sketch defining the spring form
    body = doc.addObject("PartDesign::Body", "Body")
    SketchPath = body.newObject("Sketcher::SketchObject", "Spring_Path")
    SketchPath.AttachmentSupport = (doc.getObject("XY_Plane"), [""])
    SketchPath.MapMode = "FlatFace"
    SketchPath.addGeometry(
        Part.LineSegment(Vector(-20.0, 30.0, 0.0), Vector(-20.0, 0.0, 0.0)), False
    )
    SketchPath.addConstraint(Sketcher.Constraint("PointOnObject", 0, 2, -1))
    SketchPath.addConstraint(Sketcher.Constraint("Vertical", 0))
    SketchPath.addGeometry(
        Part.ArcOfCircle(
            Part.Circle(Vector(0.0, 0.0, 0.0), Vector(0, 0, 1), 20.0),
            3.141593,
            6.283185,
        ),
        False,
    )
    SketchPath.addConstraint(Sketcher.Constraint("Tangent", 0, 2, 1, 1))
    SketchPath.addConstraint(Sketcher.Constraint("PointOnObject", 1, 2, -1))
    SketchPath.addGeometry(Part.LineSegment(Vector(20.0, 0.0, 0.0), Vector(20.0, 30.0, 0.0)), False)
    SketchPath.addConstraint(Sketcher.Constraint("Tangent", 1, 2, 2, 1))
    SketchPath.addConstraint(Sketcher.Constraint("Equal", 2, 0))
    SketchPath.ViewObject.Visibility = False

    # sketch defining the spring cross section
    SketchCircle = body.newObject("Sketcher::SketchObject", "Spring_Circle")
    SketchCircle.AttachmentSupport = (doc.getObject("XZ_Plane"), [""])
    SketchCircle.MapMode = "FlatFace"
    SketchCircle.addGeometry(Part.Circle(Vector(-20.0, 0.0, 0.0), Vector(0, 0, 1), 7.5), False)
    SketchCircle.addConstraint(Sketcher.Constraint("PointOnObject", 0, 3, -1))
    SketchCircle.ViewObject.Visibility = False

    # the spring object
    SpringObject = body.newObject("PartDesign::AdditivePipe", "Spring")
    SpringObject.Profile = SketchCircle
    SpringObject.Spine = SketchPath

    # set view
    doc.recompute()
    if FreeCAD.GuiUp:
        SpringObject.ViewObject.Document.activeView().viewTop()
        SpringObject.ViewObject.Document.activeView().fitAll()

    # analysis
    analysis = ObjectsFem.makeAnalysis(doc, "Analysis")
    if FreeCAD.GuiUp:
        import FemGui

        FemGui.setActiveAnalysis(analysis)

    # solver
    if solvertype == "elmer":
        solver_obj = ObjectsFem.makeSolverElmer(doc, "SolverElmer")
        solver_obj.OutputIntervals = [4]
        solver_obj.SimulationType = "Transient"
        solver_obj.TimestepIntervals = [21]
        solver_obj.TimestepSizes = [0.05]
        equation_deformation = ObjectsFem.makeEquationDeformation(doc, solver_obj)
        equation_deformation.setExpression("LinearTolerance", "1e-7")
        equation_deformation.LinearIterativeMethod = "Idrs"
        equation_deformation.LinearPreconditioning = "ILU1"
    else:
        FreeCAD.Console.PrintWarning(
            "Unknown or unsupported solver type: {}. "
            "No solver object was created.\n".format(solvertype)
        )
        return doc
    analysis.addObject(solver_obj)

    # material iron
    material_obj = ObjectsFem.makeMaterialSolid(doc, "Iron")
    mat = material_obj.Material
    mat["Name"] = "Iron Generic"
    mat["YoungsModulus"] = "211 GPa"
    mat["PoissonRatio"] = "0.29"
    mat["Density"] = "7874 kg/m^3"
    material_obj.Material = mat
    material_obj.References = [(body, "Solid1")]
    analysis.addObject(material_obj)

    # constraints displacement
    DisplaceLeft = doc.addObject("Fem::ConstraintDisplacement", "DisplacementLeft")
    DisplaceLeft.xFree = False
    DisplaceLeft.hasXFormula = True
    DisplaceLeft.xDisplacementFormula = 'Variable "time"; Real MATC "0.006*tx"'
    DisplaceLeft.yFree = False
    DisplaceLeft.yDisplacement = 0
    DisplaceLeft.zFree = False
    DisplaceLeft.zDisplacement = 0
    DisplaceLeft.References = [(SpringObject, "Face1")]
    analysis.addObject(DisplaceLeft)

    DisplaceRight = doc.addObject("Fem::ConstraintDisplacement", "DisplacementRight")
    DisplaceRight.xFree = False
    DisplaceRight.hasXFormula = True
    DisplaceRight.xDisplacementFormula = 'Variable "time"; Real MATC "-0.006*tx"'
    DisplaceRight.yFree = False
    DisplaceRight.yDisplacement = 0
    DisplaceRight.zFree = False
    DisplaceRight.zDisplacement = 0
    DisplaceRight.References = [(SpringObject, "Face5")]
    analysis.addObject(DisplaceRight)

    # constraints spring
    StiffnessLeft = doc.addObject("Fem::ConstraintSpring", "StiffnessLeft")
    StiffnessLeft.TangentialStiffness = "50 N/m"
    StiffnessLeft.ElmerStiffness = "Tangential Stiffness"
    StiffnessLeft.References = [(SpringObject, "Face1")]
    analysis.addObject(StiffnessLeft)

    StiffnessRight = doc.addObject("Fem::ConstraintSpring", "StiffnessRight")
    StiffnessRight.TangentialStiffness = "50 N/m"
    StiffnessRight.ElmerStiffness = "Tangential Stiffness"
    StiffnessRight.References = [(SpringObject, "Face5")]
    analysis.addObject(StiffnessRight)

    # mesh
    femmesh_obj = analysis.addObject(ObjectsFem.makeMeshGmsh(doc, get_meshname()))[0]
    femmesh_obj.Shape = body
    femmesh_obj.CharacteristicLengthMax = "1.25 mm"
    femmesh_obj.ElementOrder = "1st"
    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