The optimization calculates the von Mises stress and shows these stress values in the postprocessing as well.
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Furthermore the stress goal is dependent on the steps of the resolution levels. The stress percent goal changes between the different levels. This is a percentage value at which the target stress is reached. On the highest resolution level the requested stress goal will reach 100% an thus satisfy the defined stress goal. On lower resolution levels the stress goal varies on purpose from the requested stress goal.