Does the "structuralBC" function with "constraint' value set to "multipoint" result in free or fixed degrees of freedom?

When the function "structuralBC" is used with 'constraint'  set to 'multipoint', are the degrees of freedom (DoF) associated with each point of origin/reference considered to be 6 DoFs that are fixed or 6 DoFs that are free? 

Answer 1

[MathWorks Support Team]

When you define a "multipoint" constraint on a "Face", all nodes on that face are rigidly connected to a reference point. This reference point has 6-DoFs. This means if you move the reference point in any/all 6-DoFs, all the nodes on the associated face also move rigidly with it.

Defining a "multipoint" constraint creates neither a free nor a fixed reference point. The reference point is available for you to define interaction happening at that point with another component or ground that is connected to this reduced body. You can "fix" the reference point if you wish to do so. 

N.B.: The PDE Toolbox (which includes "structuralBC") uses the Craig-Bampton method with fixed-interface modes to produce the reduced-order matrices.