Ad 1.: If there are cracks, the Unloading direction parameter can have the described influence (as it changes the tensile unloading direction).

Ad 2.: You need to calibrate it based on the data from one experiment to predict other experiments with similar material and setup.

Regards.

Thank you very much for your reply.

I'm trying to validate results of a reinforced concrete beam, subjected to repeated loading. In my experiment, I applied repeated loading in three stages, before concrete cracking, elastic plastic range and closer to ultimate limit.
When I tried to model this, the only changing factor in the concrete material model (which I used for static loading) is the unloading factor. I set the factor as zero and tried to validate my results.
In first stage, there weren't any displacement change for all cycles, In second stage peak displacement showed less displacement change and valley displacements changed considerably. I think unloading factor has affected to this behaviour.
My questions are
                       1. Does unloading factor effect considerably for these issues?
                       2. If yes, how does it effect and how can I find a proper value?

If you still can not identify the problem source, please follow Troubleshooting, 2.1.1 to send us your model etc.

Regards.

I read the troubleshooting documents. My model is force control repeated loading system. It means I know the upper and lower load limits of my beam. I tried to apply force load case with external force monitoring points, but it did not work. How can I apply force instead of prescribed deformation and monitor the reaction forces?