Material flow simulation and experimental study of 304 stainless steel bipolar plate stamping forming

This study models and simulates anisotropic material flow to address flow inhomogeneity in stamped 0.1 mm-thick 304 stainless steel bipolar plates. A stamping model incorporating a VUMAT subroutine was developed based on the Hill48 yield criterion for 304 stainless steel. By coupling a three-dimensional orthotropic elastic matrix with the yield criterion and implementing an implicit return mapping algorithm that updates the consistent tangent stiffness, the model overcomes the limitations of conventional isotropic assumptions and accurately captures anisotropic flow behavior. Using this anisotropic stamping model, the mechanisms underlying material flow inhomogeneity were investigated, and the influencing patterns of flow velocity, stress, and strain were systematically analyzed. The simulation results indicated maximum values of 755 MPa for stress, 0.27 for strain, and 0.18 mm ms−1 for flow velocity during the stamping process. The critical influence of material anisotropy on flow velocity, stress concentration, and strain distribution was quantitatively evaluated along the rolling, transverse, and normal directions. Experimental validation revealed a maximum strain discrepancy of 6.9% between simulation and measurement. The consistency in strain distribution and fillet flow behavior confirms the model’s predictive accuracy. This study provides a reliable simulation-based framework for predicting and optimizing the high-precision stamping of bipolar plates.