## General Mechanical

#### Self-deflection of a preloaded circular plate

• Ismaël Ziane
Subscriber

Good afternoon,

I am currently working on a design that involves preloading a thin PMMA plate radially (x-y axis), the plate has an optical function and will be fixed in a preloaded state (bonded), therefore looking to check the self deflection (in the z axis) of the plate under its own weight when preloaded. Obviously, because of the preloaded state, a static structural simulation not accounting for the preload wouldn't be suitable for this exercice.

I can guess that it would mean doing a multi-step analysis somehow, but at the moment my problem resides in the fact that I would need different boundary conditions for each of the steps which questions the use of such an analysis... What is the best way to model this, a transient structural analysis? Importing the part on which the plate is going to get fixed to?

Kind Regards,

• peteroznewman
Subscriber

Please show the frame which holds the plate in the preloaded state.

Please explain how the plate is loaded when it is bonded to the frame.

Please show how the frame is connected to the optical bench.

You would use a multi-step Static Structural model where step 1 is applying the load to deform the plate to a shape, step 2 is bonding the plate to the frame, step 3 is removing the load that deformed the plate, step 4 is to change the direction of gravity or mount the frame to the optical bench.

If there is an optical prescription for the surface of the plate, then the deviation of the surface from the prescription can be measured at each step.

• Ismaël Ziane
Subscriber

Thanks Peter, I managed to do it in multi-step with your suggested steps and using contact step control for bonding!