# *************************************************************************** # * Copyright (c) 2021 Bernd Hahnebach * # * * # * 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 * # * * # *************************************************************************** import FreeCAD import Fem import ObjectsFem from . import manager from .manager import get_meshname from .manager import init_doc def get_information(): return { "name": "Lateral Torsional Buckling", "meshtype": "face", "meshelement": "Tria6", "constraints": ["displacement", "force"], "solvers": ["calculix", "ccxtools"], "material": "solid", "equations": ["buckling"] } def get_explanation(header=""): return header + """ To run the example from Python console use: from femexamples.buckling_lateraltorsionalbuckling import setup setup() See forum topic post: https://forum.freecad.org/viewtopic.php?f=18&t=20217&start=110#p510526 Simple supported I-beam with a fork support modelled with shell elements. Loaded with constant bending moment. The moment loads are done by line loads at the end of flanges. analytical solution: Mcr = 43.28 kNm = 43'280'000 Nmm flange load for a buckling factor of 1.00: 43280000 Nmm / 278.6 mm = 155348 N """ 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 objects bottom_flange = doc.addObject("Part::Plane", "Bottom_Flange") bottom_flange.Length = 10000 bottom_flange.Width = 150 top_flange = doc.addObject("Part::Plane", "Top_Flange") top_flange.Length = 10000 top_flange.Width = 150 top_flange.Placement.Base = (0, 0, 278.6) web = doc.addObject("Part::Plane", "Top_Flange") web.Length = 10000 web.Width = 278.6 web.Placement = FreeCAD.Placement( FreeCAD.Vector(0, 75, 0), FreeCAD.Rotation(0, 0, 90), FreeCAD.Vector(0, 0, 0), ) geom_obj = doc.addObject("Part::MultiFuse", "Fusion") geom_obj.Shapes = [bottom_flange, top_flange, web] 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( "Unknown or unsupported 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.GeometricalNonlinearity = "linear" solver_obj.ThermoMechSteadyState = False solver_obj.MatrixSolverType = "default" solver_obj.IterationsControlParameterTimeUse = False solver_obj.BucklingFactors = 1 analysis.addObject(solver_obj) # shell thicknesses thickness_flanges = ObjectsFem.makeElementGeometry2D(doc, 10.7, 'Thickness_Flanges') thickness_flanges.References = [(geom_obj, ("Face1", "Face2", "Face3", "Face4"))] analysis.addObject(thickness_flanges) thickness_web = ObjectsFem.makeElementGeometry2D(doc, 7.1, 'Thickness_Web') thickness_web.References = [(geom_obj, "Face5")] analysis.addObject(thickness_web) # 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, "Vertex2")] con_disp_x.xFix = True con_disp_x.xFree = False analysis.addObject(con_disp_x) con_disp_yz = ObjectsFem.makeConstraintDisplacement(doc, "ConstraintDisplacement_YZ") con_disp_yz.References = [(geom_obj, ("Edge15", "Edge16"))] con_disp_yz.yFix = True con_disp_yz.yFree = False con_disp_yz.zFix = True con_disp_yz.zFree = False analysis.addObject(con_disp_yz) # constraints force con_force_in_x = ObjectsFem.makeConstraintForce(doc, "Force_in_X") con_force_in_x.References = [(geom_obj, ("Edge3", "Edge7", "Edge8", "Edge12"))] con_force_in_x.Force = 155350 con_force_in_x.Reversed = False con_force_in_x.Direction = (geom_obj, ["Edge4"]) analysis.addObject(con_force_in_x) con_force_rev_x = ObjectsFem.makeConstraintForce(doc, "Force_rev_X") con_force_rev_x.References = [(geom_obj, ("Edge1", "Edge5", "Edge10", "Edge14"))] con_force_rev_x.Force = 155350 con_force_rev_x.Reversed = True con_force_rev_x.Direction = (geom_obj, ["Edge4"]) analysis.addObject(con_force_rev_x) # mesh from .meshes.mesh_buckling_ibeam_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, get_meshname()))[0] femmesh_obj.FemMesh = fem_mesh femmesh_obj.Part = geom_obj femmesh_obj.SecondOrderLinear = False femmesh_obj.CharacteristicLengthMax = "50.0 mm" femmesh_obj.ElementDimension = "2D" doc.recompute() return doc