Numerical Assessment of the Stamping Formability of SS304 Metallic Bipolar Plates with Side-Boss Parallel Flow Channels

Side-boss parallel channels can enhance reactant transport and water removal in proton exchange membrane fuel cells, but their local protrusions increase the forming difficulty of ultra-thin metallic bipolar plates. This study numerically investigates the single-step stamping formability of 0.1 mm SS304 bipolar plates using Dynaform. The effects of side-boss number, side-boss height, and punch speed were evaluated through thickness distribution, maximum thinning ratio, and forming-limit-diagram states. The results show that side-boss height is the dominant geometric factor. Increasing the height from 0 to 0.75 mm raises the maximum thinning ratio from 17.69% to 29.87% and shifts the critical deformation regions from the conventional channel bottom toward the side-boss roots, boss tops, transition fillets, and channel corners. The number of side-boss sets produces a non-monotonic thinning response, with maximum thinning ratios ranging from 19.54% to 27.76% for the modified configurations. Punch speeds of 200, 500, and 800 mm/s yield comparable thinning levels of 24.60%, 23.09%, and 23.16%, respectively, whereas the value increases to 26.30% at 1100 mm/s. Under the present forming conditions, these findings establish a quantitative relationship between side-boss geometry, material-flow restriction, and strain localization, and provide practical guidance for geometry selection and stamping-process design of metallic bipolar plates.