FEM ConstraintContact: Difference between revisions

Revision as of 13:44, 25 February 2021

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Menu location
FEM ConstraintContact
Model → Mechanical Constraints → Constraint contact
Workbenches
FEM
Default shortcut
None
Introduced in version
-
See also
Constraint fixed

Creates a FEM constraint for contact between 2 surfaces.

There are several ways to invoke the command:
- Press the FEM ConstraintContact button.
- Select the Model → Mechanical Constraints → Constraint contact option from the menu.
Select the master face.
Select the slave face.
Enter a contact stiffness.
Enter a friction coefficient.

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

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.

The contact stiffness should be 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 which 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 for different contact types: https://forum.freecadweb.org/viewtopic.php?f=18&t=15699&start=90#p188736
Further interesting informations:
- https://forum.freecadweb.org/viewtopic.php?f=18&t=23102#p180709 and following posts !!!
- https://forum.freecadweb.org/viewtopic.php?f=18&t=20276
- https://forum.freecadweb.org/viewtopic.php?f=18&t=21331
- https://forum.freecadweb.org/viewtopic.php?f=18&t=15699 (initial contact topic)

Materials: Solid, Fluid, Nonlinear mechanical, Reinforced (concrete); Material editor

Element geometry: Beam (1D), Beam rotation (1D), Shell (2D), Fluid flow (1D)

Constraints

Mechanical: Fixed, Displacement, Contact, Tie, Spring, Force, Pressure, Centrif, Self weight

Mesh: Mesh Netgen, Mesh GMSH, Mesh boundary layer, Mesh region, Mesh group, Nodes set, Mesh to mesh

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

Utilities: Clipping plane, Remove clipping planes, Open FEM examples; Mesh clear, Mesh display info

Additional: Preferences; FEM Install, FEM Mesh, FEM Solver, FEM CalculiX, FEM Concrete; FEM Element Types

Getting started
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@@ Line 28: / Line 28: @@
 <!--T:7-->
+# There are several ways to invoke the command:
-# Press the {{Button|[[Image:FEM_ConstraintContact.svg|16px]]}} button or choose {{MenuCommand|Model → Mechanical Constraints → [[Image:FEM_ConstraintContact.svg|16px]] Constraint contact}} from the top menu.
+#* Press the {{Button|[[Image:FEM_ConstraintContact.svg|16px]] [[FEM_ConstraintContact|FEM ConstraintContact]]}} button.
-#Select the master face.
+#* Select the {{MenuCommand|Model → Mechanical Constraints → [[Image:FEM_ConstraintContact.svg|16px]] Constraint contact}} option from the menu.
-#Select the slave face.
+# Select the master face.
-#Enter a contact stiffness.
+# Select the slave face.
-#Enter a friction coefficient.
+# Enter a contact stiffness.
+# Enter a friction coefficient.
 ==Limitations== <!--T:4-->