Defining a Nonlinear torsional spring

Question - How to define a Nonlinear torsional spring between two solid bodies in Mechanical? 

Answer - See the example attached: example_NL_torsinal_spring_R161.wbpz

Summary:
-Use two remote nodes as pilot nodes
-Use combin39 element between the pilot nodes
-Define DOF and force-deflection curve on combin39 real constants
-Solve activating Large Deflections

Click here to download example files.