Calibration and application of damage and rate-dependent constitutive model for SPCE steel

The SPCE steel demonstrates favorable deep-drawing and forming properties, leading to its widespread use in industrial production. However, when subjected to complex loads, it becomes crucial to develop a constitutive model that accurately characterizes its mechanical properties. Such a model serves as the foundation for engineering design and safety assessment. Both quasi-static tension tests and high strain rate tension tests were conducted on SPCE steel samples using static and dynamic tension testing machines at room temperature. The resulting test data was used to introduce three dynamic increase factor indicators (DIFs) that quantify the strain rate effect on SPCE steels. Additionally, the fracture morphology of typical post-test specimens was analyzed using a scanning electron microscope (SEM) to demonstrate the strain rate effect on the mechanical properties of SPCE steels from a microscopic perspective, revealing ductile fracture as the primary fracture mechanism. A double-power plastic constitutive model was developed to describe the material's tensile mechanical behavior prior to necking. Simulation analysis was performed to validate the model, and the parameters of the Ductile damage model were identified based on the simulation data. The proposed constitutive model underwent numerical verification, demonstrating good consistency between the simulation and experimental results. Furthermore, the same constitutive model was applied to process the test data of HC650 steel using the same methodology. The conclusion drawn from this analysis aligned with that of SPCE steel, confirming the suitability of the proposed constitutive model for characterizing the mechanical behavior of steels without yielding a platform under different strain rates.