It has been a long while since I used Simulation or had training on it. So after many attempts to get a proper result I have given up and hence my posting this in hopes someone can help me.

I am trying to calculate the force needed to move the piston down into the device to unseat the o-ring and allow trapped air pressure to be released out the top of the device. I have done a bench test with the actual parts and it is not coresponding with what the simulation is showing. The internal pressure can vary based on the application, but overall the design will stay the same.

So in laymans, I just want to calculate the force to apply to the top of the piston to slide it back to unseat the o-ring. How do I set this up?

Results I am getting are completely deforming the piston, or the body.

Thanks in advance!