Equivalence of cyclic-hardening among different strain path shapes and recovery of cyclic-hardening in multiaxial non-proportional cycles.

Abstract

The title problem was discussed to facilitate the formulation of constitutive models of cyclic plasticity under general multiaxial loading conditions. A series of plastic strain controlled cyclic tests was performed by applying combined axial force and torque to thin-walled tubular specimens of type 316 stainless steel at room temperature. These test consist of cyclic loadings of variable amplitudes along torsional, cruciform and circular plastic strain paths, and the combinations of cyclic loadings of different path shapes with equivalent cyclic hardening. The results of these tests showed that in the cases of torsional and cruciform cycles, the cyclic-hardening under prior cycles of larger amplitude was recoverable under the subsequent cycles of smaller amplitude, but in the case of circular cycles, the non-erasure of memory of the prior cycles was slightly observed. It was also found that the equivalence of cyclic-hardening among the cycles of different path shapes may be assumed in the formulation of a constitutive model of cyclic plasticity for general multiaxial loading conditions.