Numerical modeling of cyclic softening/hardening behavior of carbon steels from low- to high-cycle fatigue regime

The aim of this study is to characterize the stress-strain behavior of three construction steels (SM490, SM570, and F18B) through both experimental and numerical investigations. The material performance was evaluated by conducting tests on round bar specimens subjected to monotonic, fatigue, and incremental step fully reversed loading conditions. The experimental campaign was conducted to provide valuable information on the mechanical performances of the steels and data for calibrating the material constants required for numerical analyses. The numerical simulations aimed to demonstrate the effectiveness of the proposed unconventional plasticity model, the Fatigue SS model (FSS), in describing the non-linear behavior of the materials under a broad range of loading conditions, including stress states below and beyond the macroscopic yield condition. This aspect is a significant advantage of the FSS model, as conventional elastoplastic theories fail to provide a phenomenological description of inelastic material deformation under stress states within the yield condition. The good agreement between the experimental and numerical results confirms the validity of the calibration of the material constants and the reliability of the computational approach.