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Hi all,

Anyone here know/have done the right way to set an initial displacement for electromechanical (EMI) physics?

Basically the geometry is based on a simple parallel plate capacitor with fixed bottom plate and moving top plate. The top plate is fixed at all end, so they will bend down to bottom plate when potential difference is applied. The simulation is quite straightforward with the EMI physics.

What I am trying to do is to impose an initial displacement or bending for the top plate; before actuating it. The initial displacement is due to layer stress, which made it bent upward after underetching of the sacrificial layer.

I've tried prescribed displacement in Solid Mechanics; then use the resulting stress as initial stress (solid.sx,solid.sxy,...) in the EMI, but they bend differently. For example if i impose a 2um initial displacement, I get -1.4um (downward) initial displacement in EMI.

But if i use the resulting stress in another Solid Mechanics physics as initial stress, I get the right initial displacement; i.e. 2um prescribed displacement in 1st. Solid Mechanics results in 2um displacement in 2nd Solid Mechanics.

Is there some condition or setting limitating the EMI physics from getting the right stress value from the Solid Mechanics physics?

Many thanks in advance =)