Reply To: Mode is 0 and circular beams

[peteroznewman]

The wheel is free to spin on the shaft.  That means there is zero stiffness in the rotational direction, which results in a zero frequency.  After you change the revolute joint to a fixed joint, the wheel now has a stiffness to ground in the rotational direction and you get a non-zero frequency.  I explained how the intertial load of rotational velocity works in your other discussion.