Then, you can just ignore the circle and apply the forces directly in the point A.

What I was trying to indicate was that I was aware of the small discrepancy in the final position of the point F; and that because the angles involved are chosen to be very small at each step of the iterations; the affect of that discrepancy is minimal for each step.

However, the forces that will result from the next iteration of the stress tensor, are affected by the rotation of the body from the previous step, hence it cannot be ignored completely.

It is clear that those small errors will accumulate through the iterations; and if once the model is run -- it'll take many days -- if the accumulated error is too large, which will be obvious once I can see the final position of the body -- it should end up back where it started once the assembly has made a full revolution around B which is my terminating condition -- then I will have a handle on what kind of additional calculation (or possibly a fudge factor) I need to incorporate at each step to alleviate the error accumulation.