OOF: Finite Element Analysis of Microstructures

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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 $x$ and $y$ degrees of freedom are treated separately, so a node can be a boundary node for $x$ and not for $y$, 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 $y$ degrees of freedom on the top edge of the sample and apply a $y$ force to it.

Menus Functions Variables
fix show  
free apply  

The Submenus are:

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

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