Hi,
In order to calculate a displacement, you need to have a node which implies that you need an element. So you probably want to draw a line that represents the axis of the port, and then tie the axis to some of the nodes around the openings of the port.
Conceptually, using the "Mesh > CAD Additions > Bolt" with a head diameter and nut diameter of 0 will draw a line along the centerline of the port and connect the ends of this "axis" to the nodes around the perimeter of the opening. (Depending on the geometry, you might need to use different commands like "Mesh > CAD Additions > Joint", drawing the axis manually and using "Draw > Design > Centroid Creator" to join the axis to the nodes around the port opening.)
You'll probably want to define these new elements as beam elements and enter small cross sectional properties so that the stiffness does not influence the flexibility of your model.
In the results, you'll be able to see how the axis moves (displacement), rotates, etc.
