Constraints are conditions that you can apply to edges of a Designer model. Unlike boundary conditions, constraints can be placed on any edge of a model, not just at the domain edges. Constraints are useful to use when you have two different materials at a domain edge such as sensor material and load material, using constraints you can fix the sensor material and make the load material absorbing. Constraints can be found in the Model Tree in Designer Mode at Model > Boundary Conditions > Constraints.
A user can add constraints to their model using the plus icon. Constraints are set up by choosing one of the four a constraint types and specifying the region in which to apply this constraint.
Free (default for all edges of model)
Definition: Nodes can move freely with no external forces acting upon them
Restrictions: None
Absorbing
Definition: Represents an infinite media where energy continues past the boundary with no reflections
Restrictions: Must be used between void and another material. Cannot be placed between two non-void materials.
Fixed
Definition: Nodes are completely fixed (zero displacement) and energy is perfectly reflected
Restrictions : None
Impedance
Definition: Nodes have the mass and stiffness values of an infinite load of the given material.
Restrictions: Must be used between void and another material. Cannot be placed between two non-void materials.