A note on formulations of static shakedown analysis with bounded kinematic hardening

Two different formulations for the two-surface model of bounded kinematic hardening can be found in literature on shakedown analysis with the von Mises yield criterion. This short paper explains that these two formulations are not equivalent, although there exists literature asserting that they are equivalent. More specifically, the formulation using the constraint on the stress is not a sufficient condition for the two-surface model. Consequently, the static shakedown analysis using this formulation over-evaluates the shakedown factor in general.