FEM Workbench/ja

はじめに

ワークフロー

FreeCAD 0.15以降、FEM WorkbenchはWindows、MacOSX、Linuxプラットフォームで使用できます。 ワークベンチは外部ソルバーを使用するため、手動セットアップの量は使用しているオペレーティングシステムによって異なります。 外部ツールの設定方法については、 FEM Installページを参照してください。

Workflow of the FEM Workbench; the workbench calls two external programs to perform meshing of a solid object, and perform the actual solution of the finite element problem

メニュー：モデル

• Analysis container: Creates a new container for a mechanical analysis.

材料

• Material for solid: Lets you select a solid material from the database.

• Material for fluid: Lets you select a fluid material from the database.

• Nonlinear mechanical material: Lets you add a nonlinear mechanical material model.

• Reinforced material (concrete): Lets you select reinforced materials consisting of a matrix and a reinforcement from the database.

• Material editor: Lets you open the material editor to edit materials.

要素の幾何学

• Beam cross section: Used to define cross sections for beam elements.

• Beam rotation: Used to rotate cross sections of beam elements.

• Shell plate thickness: Used to define shell element thickness.

• Fluid section for 1D flow: Used to create fluid section element for pneumatic and hydraulic networks.

Electromagnetic boundary conditions

• Electrostatic potential boundary condition: Used to define electrostatic potential.

• Current density boundary condition: Used to define a current density. introduced in 0.21

• Magnetization boundary condition: Used to define a magnetization. introduced in 0.21

• Electric charge density: Used to define electric charge density load. introduced in 1.1

• Initial flow velocity condition: Used to define an initial flow velocity for a body (volume).

• Initial pressure condition: Used to define an initial pressure for a body (volume). introduced in 0.21

• Flow velocity boundary condition: Used to define a flow velocity as a boundary condition at an edge (2D) or face (3D).

Geometrical analysis features

• Plane multi-point constraint: Used to define a constraint for keeping the nodes on a planar surface on the same plane.

• Section print feature: Used to print the predefined facial output variables (forces and moments) to the data file.

• Local coordinate system: Used to define a local coordinate system for a face.

• Fixed boundary condition: Used to define a fixed boundary condition on point/edge/face(s).

• Rigid body constraint: Used to apply the CalculiX's rigid body constraint that constrains the motion of the nodes of a selected geometrical entity to the motion of a reference point positioned by the user. introduced in 1.0

• Displacement boundary condition: Used to define a displacement boundary condition on point/edge/face(s).

• Contact constraint: Used to define a contact constraint between two faces.

• Tie constraint: Used to define a tie constraint ("bonded contact") between two faces, or, introduced in 1.0, cyclic symmetry.

• Spring: Used to define a spring. introduced in 0.20

• Force load: Used to define a force in [N] applied uniformly to the selected face in the defined direction.

• Pressure load: Used to define a pressure load.

• Centrifugal load: Used to define a centrifugal force body load. introduced in 0.20

• Gravity load: Used to define a gravity acceleration acting on a model.

• Initial temperature: Used to define the initial temperature of a body.

• Heat flux load: Used to define a heat flux load on a face(s).

• Temperature boundary condition: Used to define a temperature boundary condition on a point/edge/face(s).

• Body heat source: Used to define an internally generated body heat.

Overwrite Constants

• Constant vacuum permittivity: Used to overwrite the permittivity of vacuum with a custom value.

メニュー：メッシュ

• FEM mesh from shape by Netgen: Generates a finite element mesh for a model using Netgen.

• FEM mesh from shape by Gmsh: Generates a finite element mesh for a model using Gmsh.

• FEM mesh boundary layer: Creates anisotropic meshes for accurate calculations near boundaries.

• FEM mesh region: Creates a localized area(s) to mesh which highly optimizes analysis time.

• FEM mesh group: Groups and labels elements of a mesh (vertex, edge, surface) together, useful for exporting the mesh to external solvers.

• Erase Elements: Hides elements selected by a polygon from the mesh. introduced in 1.0

• FEM mesh to mesh: Converts surfaces of 3D elements or whole 2D elements of a selected FEM mesh to surface mesh.

メニュー：Solve

• Solver CalculiX Standard: Creates a new solver for this analysis.

• Solver Elmer: Creates the solver controller for Elmer.

• Solver Mystran: Creates the solver controller for the MYSTRAN solver. introduced in 0.20

• Solver Z88: Creates the solver controller for Z88.

Mechanical equations

• Elasticity equation: Equation for the Solver Elmer to perform linear mechanical analyses.

• Deformation equation: Equation for the Solver Elmer to perform nonlinear mechanical analyses (deformations). introduced in 0.21

Electromagnetic equations

• Electrostatic equation: Equation for the Solver Elmer to perform electrostatic analyses.

• Electricforce equation: Equation for the Solver Elmer to calculate the electric force on surfaces.

• Magnetodynamic equation: Equation for the Solver Elmer to calculate magnetodynamics. introduced in 0.21

• Magnetodynamic 2D equation: Equation for the Solver Elmer to calculate magnetodynamics in 2D. introduced in 0.21

• Static current equation: Equation for the Solver Elmer to calculate static current conduction. introduced in 1.1

• Flow equation: Equation for the Solver Elmer to perform flow analyses.

• Flux equation: Equation for the Solver Elmer to perform flux analyses.

• Heat equation: Equation for the Solver Elmer to perform heat transfer analyses.

• Solver job control: Opens the menu to adjust and start the selected solver.

• Run solver calculations: Runs the selected solver of the active analysis.

メニュー：結果

• Purge results: Deletes the results of the active analysis.

• Show result: Used to display the result of an analysis. This dialog is not available for the Solver Elmer as this solver visualizes using the Post pipeline from result object only.

• Apply changes to pipeline: Toggles if changes to pipelines and filters are applied immediately.

• Post pipeline from result: Used to add a new graphical representation of FEM analysis results (color scale and more display options).

• Pipeline branch: Used to branch the results pipeline. introduced in 1.1

• Warp filter: Used to visualize the scaled deformed shape of the model.

• Scalar clip filter: Used to clip a field with a specified scalar value.

• Function cut filter: Used to display the results on a sphere or a plane cutting through the model.

• Region clip filter: Used to clip a field with a sphere or a plane cutting through the model.

• Contours filter: Used to display iso-lines (for analyses in 2D) or iso-contours. introduced in 0.21

• Line clip filter: Used to plot the values of a field along a specified line.

• Stress linearization plot: Creates a stress linearization plot.

• Data at point clip filter: Used to display value of a selected field at a given point.

• Calculator filter: Used to create custom fields by evaluating expressions operating on the existing fields. introduced in 1.1

Filter functions

• Plane: Cuts the result mesh with a plane.

• Sphere: Cuts the result mesh with a sphere.

• Cylinder: Cuts the result mesh with a cylinder. introduced in 0.21

• Box: Cuts the result mesh with a box. introduced in 0.21

メニュー：ユーティリティ

• Clipping plane on face: Adds a clipping plane for the whole model view.

• Remove all clipping planes: Removes all existing clipping planes.

• Open FEM examples: Open the GUI to access FEM examples.

コンテキストメニュー

• Clear FEM mesh: Deletes the mesh file from the FreeCAD file. Useful to make a FreeCAD file lighter.

• Display FEM mesh info: Displays basic statistics of existing mesh - number of nodes and elements of each type.

Obsolete tools

• Fluid boundary condition: Used to define a fluid boundary condition. Did not have a solver. Not available in 1.0 and above.

• Constraint bearing: Used to define a bearing constraint. Did not have a solver. Not available in 1.0 and above.

• Constraint gear: Used to define a gear constraint. Did not have a solver. Not available in 1.0 and above.

• Constraint pulley: Used to define a pulley constraint. Did not have a solver. Not available in 1.0 and above.

• Solver CalculiX (new framework): Same as the original framework Solver CalculiX Standard with extra checks. Tool was unfinished. Not available in 1.0 and above.

• Nodes set: Creates/defines a node set from FEM mesh. Tool was unfinished and couldn't be used. Not available in 1.0 and above.

環境設定

• Preferences...: Preferences available in FEM Tools.

リンク

FEMインストールをクリックすると、動作中のFEMモジュールを設定する方法の詳細が表示されます。

The following pages explain different topics of the FEM Workbench.

FEM Install: a detailed description on how to set up the external programs used in the workbench.

FEM Geometry Preparation and Meshing: tips regarding geometry preparation for FEM and meshing.

FEM Mesh: details about meshes in the FEM workbench.

FEM Solver: further information on the different solvers available in the workbench, and those that could be used in the future.

FEM CalculiX: further information on CalculiX, the default solver used in the workbench for structural analysis.

FEM Concrete: interesting information on the topic of simulating concrete structures.

Tutorials

Tutorial 2: FEM Tutorial; simple tension analysis of a structure.

Tutorial 3: FEM Tutorial Python; set up the cantilever example entirely through scripting in Python, including the mesh.

Tutorial 4: FEM Shear of a Composite Block; see the deformation of a block that is comprised of two materials.

Tutorial 5: Transient FEM analysis

Tutorial 6: Post-Processing of FEM Results with Paraview

Tutorial 7: FEM Example Capacitance Two Balls; Elmer's GUI tutorial 6 "Electrostatics Capacitance Two Balls" using FEM Examples.

Coupled thermal mechanical analysis tutorials by openSIM

Video tutorial 1: FEM video for beginner (including YouTube link)

Video tutorial 2: FEM video for beginner (including YouTube link)

Many video tutorials: anisim Open Source Engineering Software (in German)

Extending the FEM Workbench

The FEM Workbench is under constant development. An objective of the project is to find ways to easily interact with various FEM solvers, so that the end user can streamline the process of creating, meshing, simulating, and optimizing an engineering design problem, all within FreeCAD.

The following information is aimed at power users and developers who want to extend the FEM Workbench in different ways. Familiarity with C++ and Python is expected, and also some knowledge of the "document object" system used in FreeCAD is necessary; this information is available in the Power users hub and the Developer hub. Please notice that since FreeCAD is under active development, some articles may be too old, and thus obsolete. The most up to date information is discussed in the FreeCAD forums, in the Development section. For FEM discussions, advice or assistance in extending the workbench, the reader should refer to the FEM subforum.

The following articles explain how the workbench can be extended, for example, by adding new types of boundary conditions (constraints), or equations.

• Extend FEM Module
• Onboarding FEM Devs attempts to orient new devs on how to contribute to the FEM workbench.
• Add FEM Constraint Tutorial
• Add FEM Equation Tutorial

A developer's guide has been written to help power users in understanding the complex FreeCAD codebase and the interactions between the core elements and the individual workbenches. The book is hosted at github so multiple users can contribute to it and keep it updated.

• Early preview of ebook: Module developer' guide to FreeCAD source forum thread.
• FreeCAD Mod Dev Guide github repository.

Extending the FEM Workbench documentation

• More information regarding extending or missing FEM documentation can be found in the forum: FEM documentation missing on the Wiki