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Re: incremental formulation normal force

 


I need the incremental formulation for the normal force in the contact
law. Could you tell me how to do that?
What is the problem exactly? You have the equation but you don't know how to implement it, or you have no equation? Why do you need the incremental formulation? Do you have irreversible non-linearities?

 Should I simply used the
normalVelocity component computed at contact as we do for the shear
force? What about the sign convention? Should it remain the same,
right?
Yes and yes.

Or if you want to go more precise, you could store previous normal
deformation, then compute the current one (total formulation), divide by
Δt to get increment and add it to previous incremental normal
deformation...
Mmmmh... It is not so complicated but wouldn't it be exactly the same?
Un(t+dt)=Un(t) + dt[(Un(t+dt)-Un(t))/dt]?
Or the rotation of the normal makes the difference? In that case I'd store the previous Un and use the increment dUn=U(t+dt)-U(t) as you suggest.

Bruno



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