Numerical-experimental investigations on the manufacturing of an aluminium bipolar plate for proton exchange membrane fuel cells by warm hydroforming

This research study focuses on the manufacturing of a bipolar plate used in proton exchange membrane fuel cells. In particular, the authors investigate the manufacturing of the part by means of warm hydroforming, adopting an aluminium alloy (AA6061) as sheet material. Both the channel profile (the reagent channel width and the die upper radius), and the bipolar plate geometries (in terms of channel layouts) are investigated by means of finite element simulations. Preliminary experimental investigations were carried out in order to define both the mechanical (flow curves) and strain behaviours (forming limit curves) of the adopted aluminium alloy according to temperature and strain rate. Subsequent finite element investigations aimed to define the channel profile by means of 2D models: a statistical approach was used to evaluate the dimension of the reagent channel width, the die upper radius and the sheet thickness. Finally, proposed bipolar plate geometries were investigated by running 3D simulations at different working temperatures and oil pressures in order to evaluate: (1) the bipolar plate geometry able to avoid regions with critical thinning and (2) suitable parameters for the warm hydroforming process.