Boundary Conditions

A simulation won’t run — or will give meaningless results — unless it knows what is held fixed and what is allowed to move. Boundary conditions are how you express that.

For example, in a tension test the two ends of a specimen are gripped: one end is held still, the other is pulled. Those grips are boundary conditions. Without them the whole part would just float away.

A condition is set for one block and points in one direction:

Setting	What it controls
Name	A label for the condition.
Type	What kind of condition this is (fixed, prescribed displacement, and so on).
Block id	The block the condition applies to.
Coordinate	The direction the condition acts in (X, Y, or Z).
Value	The value the condition applies, for example how far the block moves.

The built-in models come with the right boundary conditions already set up. You usually only need to adjust them when building a model of your own.