Impact loading response and plasticity stress flow analysis of multilayer low carbon steel: A study of mechanical properties and deformation characteristics

Multilayer ST12 steel is extensively utilized in the forming industry due to its superior ductility and energy absorption properties. This study presents a combined theoretical and experimental investigation to characterize the plasticity stress flow, calibrate the Johnson-Cook (JC) material parameters for low-carbon steel, and evaluate the impact behavior of multilayer ST12 steel under dynamic loading conditions. The quasi-static stress-strain response was analyzed using experimental and numerical methods, employing five theoretical models. JC model parameters for ST12 steel were calibrated based on quasi-static and dynamic tensile tests, while the impact response of one-, two-, and three-layers configurations was evaluated across varying speeds. Equations of the adiabatic temperature rise related to the specific heat capacity was calculated. Results indicated that layer integration increased impact acceleration and reduced displacement, with the two-layer sheet demonstrating greater energy absorption than the three-layer sheet across all tested speeds. Numerical predictions closely matched experimental results, with deviations of less than 8%. Additionally, two modified Models were introduced for the evaluation of two common models, isotropic hardening and power law, which demonstrated a high level of agreement with the experimental results, exceeding 90%. This research provides critical insights for predicting stress thresholds, plasticity, fracture initiation, and nonlinear behavior, offering a robust framework for evaluating mechanical properties. It elucidates the impact response of multilayer steel, laying the groundwork for advanced nonlinear and quasi-static and impact analyses. Also, the findings serve as a foundation for future investigations into the behavior of multilayer steels under diverse loading conditions. • Modified isotropic hardening, power law, and bimodal models can characterize stress-strain curves with more than 90% accuracy. • The failure and Constitutive Johnson-Cook models after calibration material parameters predicted the experimental impact test, with 94% accuracy. • Layer integration increased impact acceleration and reduced displacement and energy absorption, across all tested speeds • Based on the adiabatic temperature effect equations, the adiabatic temperature rise decreases with increasing test temperature, while does not rise significantly with the increase of strain rate. • Both two theoretical approaches, the bimodal and Johnson-Cook models, have equivalent estimates for impact testing at different speeds.