If you want to simulate torque applied to the gear, you can also do it using a rigid body constraint. This approach will be easier. Just create a reference point in the middle of the gear, select it for rigid body constraint, pick a face or an edge to which the load will be transferred and define Moment load assigned to the reference point. Like in this tutorial: https://youtu.be/2upPxL45OZg
When it comes to the analysis with contact, I would do it differently, using the procedure described here:
You already have refined mesh and contact pair so just consider running a plane stress analysis for a start and use rigid body constraints (necessary to operate on rotational degrees of freedom for solid elements) to apply BCs to gears - you can make one gear free to rotate and apply angle of rotation to another gear. Torque will be worse for convergence.
Here’s a modified version of your model:
In addition to the aforementioned suggestions I made the following changes:
- removed unnecessary faces from contact pair
- replaced two sections with one since you have a single material
- removed tie constraint (not needed here)
- removed centrifugal load (not necessary when actual rotation is simulated)