why we use an OFFSET for the objective = Compliance in a Topology optimization

Hi,

I wonder why we use an OFFSET for the objective = Compliance  in a Topology optimizationto have more iteration before that the result converge? 

this is usually used if we want to optimize a small componant attached to a big domain 

In the picture i show the new axis ( in red ) after an offset equation 

Thank you 

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