Enhancing plasticity modeling of DC04 steel using strain-dependent Hill 1948 and BBC 2005 yield criteria: a novel 2D-DIC approach to track anisotropy

The texture evolution during deformation significantly influences the mechanical properties of metals, including strength, formability, and anisotropy. Neglecting the evolution of anisotropy due to texture changes in plasticity models can lead to inaccurate stress predictions, unrealistic material behavior, limited formability assessments, and challenges in material optimization. This study addresses these limitations by enhancing the quadratic Hill 1948 and nonquadratic BBC 2005 yield criteria, incorporating strain-dependent anisotropy parameters to accurately represent the mechanical behavior of DC04 steel. Uniaxial tensile tests were conducted at 22.5° intervals relative to the rolling direction to extract the material’s mechanical properties. The quadratic Hill 1948($\overline{\epsilon }$) and nonquadratic BBC 2005($\overline{\epsilon }$) yield functions were employed, with their parameters evolving as a function of equivalent strain. A novel approach utilizing a 2D digital image correlation (2D-DIC) system was introduced to track anisotropy evolution by analyzing the behavior of multiple points across the deformation region. The anisotropy parameters of the BBC 2005 yield criterion were determined through uniaxial tensile test data and optimization of an error function via the Levenberg–Marquardt algorithm. The strain-hardening behavior of the material was described via the Swift hardening law. After validation, the models were implemented into a user-defined material subroutine (UMAT) for finite element simulations in ABAQUS, and the results were compared with experimental data. This study demonstrates a significant improvement in the accuracy of modeling the plastic behavior of DC04 steel by incorporating the evolution of anisotropy within the yield criterion, driven by texture evolution.