FEM ConstraintContact/de: Difference between revisions
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==Einschränkungen== |
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* The contact constraint can only be applied to two faces. |
* The contact constraint can only be applied to two faces. |
Revision as of 11:22, 3 October 2023
FEM RandbedingungKontakt |
Menüeintrag |
---|
Modell → Mechanische Randbedingungen und Lasten → Randbedingung Kontakt |
Arbeitsbereich |
FEM |
Standardtastenkürzel |
Keiner |
Eingeführt in Version |
- |
Siehe auch |
FEM RandbedingungFestsetzen |
Beschreibung
Erstellt eine FEM-Randbedingung für den Kontakt zwischen zwei Oberflächen.
Anwendung
- Es gibt mehrere Möglichkeiten den Befehl aufzurufen:
- Die Schaltfläche Randbedingung Kontakt drücken.
- Den Menüeintrag Modell → Mechanische Randbedingungen und Lasten → Randbedingung Kontakt auswählen.
- Die Hauptfläche auswählen.
- Die untergeordnete Fläche auswählen.
- Eine Kontaktsteifigkeit eingeben.
- Einen Reibungskoeffizienten eingeben.
Einschränkungen
- The contact constraint can only be applied to two faces.
- Development for multiple contact at once: https://forum.freecadweb.org/viewtopic.php?f=18&t=15699&start=130#p303275
- Because multiple meshes are currently not supported, contact must be applied to faces that are separated by (at least) a small distance. If the faces were touching (no gap between them), the result of a boolean union or boolean fragments operation (necessary to avoid having multiple meshes which is not allowed at the moment) would be a continuous mesh and thus no need to use contact anymore. See Forum discussion.
Hinweise
Tips for modeling
- from https://forum.freecadweb.org/viewtopic.php?f=18&p=340874#p340494
- Better use linear elements otherwise calculations are very time consuming
- master/slave assignment:
- The larger of the two surfaces should act as the master surface.
- If the surfaces are of comparable size, the surface on the stiffer body should act as the master surface.
- If the surfaces are of comparable size and stiffness, the surface with the coarser mesh should act as the master surface.
CalculiX
- The contact stiffness can be estimated as 10 times the Young's modulus of the material for hard contact. The higher the value for contact stiffness, the harder the contact between surfaces.
- The slave face is the face that penetrates into the master face and therefore experiences more deformation.
- The *CONTACT PAIR card is used for modeling contact in CalculiX. The constraint uses Face-to-Face penalty contact and the contact formulation is explained in detail at http://web.mit.edu/calculix_v2.7/CalculiX/ccx_2.7/doc/ccx/node112.html
- Overview of different contact types: https://forum.freecadweb.org/viewtopic.php?f=18&t=15699&start=90#p188736
- Further interesting information:
- A very detailed CalculiX contact example. (link)
- An interesting example found in the FreeCAD German subforum. (link)
FEM
- Materials: Solid, Fluid, Nonlinear mechanical, Reinforced (concrete); Material editor
- Element geometry: Beam (1D), Beam rotation (1D), Shell (2D), Fluid flow (1D)
Constraints
- Electromagnetic: Electrostatic potential, Current density, Magnetization
- Geometrical: Plane rotation, Section print, Transform
- Mechanical: Fixed, Displacement, Contact, Tie, Spring, Force, Pressure, Centrif, Self weight
- Thermal: Initial temperature, Heat flux, Temperature, Body heat source
- Overwrite Constants: Constant vacuum permittivity
- Solve: CalculiX Standard, Elmer, Mystran, Z88; Equations: Deformation, Elasticity, Electrostatic, Electricforce, Magnetodynamic, Magnetodynamic 2D, Flow, Flux, Heat; Solver: Solver control, Solver run
- Results: Purge, Show; Postprocessing: Apply changes, Pipeline from result, Warp filter, Scalar clip filter, Function cut filter, Region clip filter, Contours filter, Line clip filter, Stress linearization plot, Data at point clip filter, Filter function plane, Filter function sphere, Filter function cylinder, Filter function box
- Additional: Preferences; FEM Install, FEM Mesh, FEM Solver, FEM CalculiX, FEM Concrete; FEM Element Types
Anwenderdokumentation
- Erste Schritte
- Installation: Herunterladen, Windows, Linux, Mac, Zusätzlicher Komponenten, Docker, AppImage, Ubuntu Snap
- Grundlagen: Über FreeCAD, Graphische Oberfläche, Mausbedienung, Auswahlmethoden, Objektname, Programmeinstellungen, Arbeitsbereiche, Dokumentstruktur, Objekteigenschaften, Hilf FreeCAD, Spende
- Hilfe: Tutorien, Video Tutorien
- Arbeitsbereiche: Std Base, Arch, Assembly, CAM, Draft, FEM, Inspection, Mesh, OpenSCAD, Part, PartDesign, Points, Reverse Engineering, Robot, Sketcher, Spreadsheet, Surface, TechDraw, Test Framework