Triphasic ratcheting strain prediction of materials over stress cycles

ABSTRACT

This study intends to formulate ratcheting strain evolution in steel alloys of 42CrMo, 20CS, SA333 Gr. 6 C-Mn and OFHC copper over uniaxial stress cycles. Stages of ratcheting deformation were related to stress cycles, lifespan, mechanical properties and amplitude and mean stress components by means of linear and nonlinear functions. Terms of mechanical properties in the ratcheting formulation enabled to characterize ratcheting response of various materials over life cycles. These terms were further employed to interpret the influence of softening/hardening response of materials on ratcheting deformation. Ratcheting data for 42CrMo, 20CS, SA333 steels and OFHC copper reported in the literature were employed to evaluate the proposed ratcheting formulation. The predicted ratcheting strain values based on the proposed equation were found in good agreements as compared with the experimental data.