How to apply forces on a gear pump shaft

Faker

Hi everyone,
I’m working on a small FEM project in HyperMesh (OptiStruct) on a gear pump's shaft.

The problem is how to properly apply the gear forces in order to get results that make sense and that it remains stable when refining the mesh.

What I tried:

1. Pressure on 3 gear teeth flanks (the gear has a total of 12 teeth).
   - I converted 260 bar to 26 MPa and used magnitude = 26.
   But in when I run the simulation, the shaft gets unrealistically deformed like it's made of rubber.
2. Distributing resultant loads using RBE elements (rigids).
   - I tried to connect many nodes on the gear/tooth region to a reference node (to apply the forces/moments and distribute them).
   - If I use many rigids, OptiStruct throws “Error 179”.
   - From some googling it might be related to limitations of the student license, but I’m not sure.

Does anyone have any suggestion?

SHAFT:  https://prnt.sc/9HP74JSOFI13

1° version with few rigids:  https://prnt.sc/9T1qpiyAPOnA

1° version stress results:  https://prnt.sc/1JfUVGJE3ZE1

2° version with a lot of rigids (failed when running):  https://prnt.sc/PQNpYYefJ0n3