ON SOME MODIFICATIONS OF KINEMATIC HARDENING TO IMPROVE THE DESCRIPTION OF RATCHETTING EFFECTS

The constitutive modeling of cyclic plasticity has made great progress during the past 20 years. One of the unsolved difficulties concerns the problem of ratchetting, that is, the progressive strain accumulation, cycle-by-cycle, induced by the superposition of a cyclic secondary load to a constant primary load (the mean-stress in the tension-compression case). This paper considers several special kinematic hardening rules and their properties in tension-compression. One particular rule is selected which offers a good compromise, describing both the shape of the normal cyclic stress-strain relations and the ratchetting results. A complete model is then developed including isotropic hardening, which describes fairly well the monotonic, cyclic and ratchetting behaviour of type 316 L stainless steel at room temperature.