Changing an analysis parameter during cycling

Is it possible to change a parameter during cycling in FLAC3D?

For example, I want to check the effective stress value at a zone or the shear force value at a structural element at each time step or at specific time intervals. When running the analysis, I want to change the stiffness/strength parameter of the zone/structural element based on the level of the value I checked.

Can it be done by fish scripting?

Yes, fish-call does the job. Refer to the doc of fish-call under the command model solve.

The command fish callback is helpful as well.

Great! Thank you very much.