ON MODELING OF KINEMATIC HARDENING FOR RATCHETING BEHAVIOR

A kinematic hardening rule is formulated on the assumption that each c omponent ai of back stress has a critical state for its dynamic recove ry to be fully activated. The rule has a feature that only the project ion of plastic strain rate to the direction of alpha(i) contributes to the dynamic recovery. This is in contrast with previous rules in whic h the accumulated plastic strain rate enters into the dynamic recovery term. Applying the present and previous rules to experiments of modif ied 9Cr-1Mo steel at 550 degrees C, we discuss effects of the feature mentioned above on simulating the multiaxial as well as uniaxial ratch eting behaviour.