A Cyclic Visco-Plastic Constitutive Model for the Ratcheting Behavior of U75VG Rail Steel under a Wide Range of Loading Rates

The uniaxial tension, strain-controlled and stress-controlled cyclic deformation experiments of U75VG rail steel at various loading rates were carried out. Experimental results show that the U75VG rail steel shows obvious rate-dependent tension, cyclic softening feature and ratcheting behavior. Moreover, based on the rate-dependent experimental results, a new cyclic visco-plastic constitutive model was established by introducing the rate-dependent isotopic resistance and ratcheting factor into isotropic and kinematic hardening rules, respectively. Compared with the classic cyclic visco-plastic model, the proposed model can reasonably simulate the tension, strain-controlled and stress-controlled cyclic deformation behaviors at different loading rates. Finally, the prediction capacity of ratcheting behavior under a wide range of loading rates was demonstrated.