Numerical investigation of formed residual stresses and the thickness of stainless steel bipolar plate in PEMFC

• The formed BPP has a large residual stress, especially in the bending zone.
• The formed BPP thickness is non-uniform along the surface of BPP.
• The geometry dimensions have a great effect on residual stress and formed thickness.

Stainless steel bipolar plates are regarded as a good substitute for traditional graphite bipolar plates in proton exchange membrane fuel cells. Stamping is a first selection for the manufacture of stainless steel bipolar plates. In addition to paying more attention to the stamping channel shape, a good prediction, and an efficient evaluation of the formed residual stress and thinning of bipolar plates are necessary. In this paper, the formed stress and deformation of SS304 stainless steel BPP with a thickness of 0.1 mm was investigated by a 2D plane strain FE model. Numerical results showed that formed BPP has a large residual stress, especially in the bending zone. Residual stresses distribution along the inner surface, outer surface, and direction of thickness was non-uniform. Geometrical dimensions have a great effect on residual stress and formed thickness. With an increase of the upper die width and die depth, the peak residual stress increased, and the formed thickness became less uniform. With an increase of the curve radius, the residual stress decreased, and the formed thickness became more uniform.