# OOF: Finite Element Analysis of Microstructures

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*/bc*

This Submenu has methods for setting boundary conditions, or removing
degrees of freedom from the nodes.
In *OOF*, *boundary nodes* are nodes whose positions are fixed and
therefore aren't solved for by the *equilibrate* command.
Actually, the and degrees of freedom are treated separately,
so a node can be a boundary node for and not for , and vice
versa. The */bc* menu determines which degrees of freedom are on
the boundary, but does not determine the positions of those degrees of
freedom. The */distort* menu sets the positions of the boundary
degrees of freedom.

The *bc* menu also is used to *enslave* degrees of freedom to
one another. Enslaved degrees of freedom all have the same
displacement. In other words, they're all actually just one single
degree of freedom. Enslaved degrees of freedom may also be fixed (*ie,* on the boundary), in which case they aren't very interesting,
because their positions won't change during equilibration, and the
fact that they're enslaved is irrelevant. Enslaved degrees of freedom
which aren't fixed, however, change their positions in unison during
equilibration. For example, to simulate a system below a rigid
plate with a weight on it, you'd enslave the degrees of freedom on
the top edge of the sample and apply a force to it.

Menus |
Functions |
Variables |

fix | show | |

free | apply | |

enslave | ||

emancipate | ||

groups |

The Submenus are:

**fix**- Fix a degree of freedom. See section 3.22
**free**- Remove boundary conditions at nodes. See section 3.23.
**enslave**- Enslave the nodes in a group. See section 3.24.
**emancipate**- Emancipate (
*ie,*un-enslave) the nodes in a group. See section 3.25. **groups**- Manage node groups (same as Submenu
*/groups/nodes*). See section 3.17.

**Subsections**

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