I am currently modeling a nanoindentation simulation in Abaqus Explicit. I have 2 steps: indenter indentation and indenter retraction. The indenter is modeled as rigid. I have two constraints setup: a rigid body constraint and a coupling constraint to tie the indenter nodes to the reference point. During the indentation step, everything works perfectly and the rigid indenter follows the assigned reference point. During the retraction step, however, the reference point retracts back to the original position while the rigid body continues to move in the same direction as the previous step. The constraints remain active throughout the simulation. I am not sure why the rigid body follows the reference point for one step and then moves in the opposite direction the next. Thank you!