Numerical Study on the Stress Concentration Phenomenon in the Membranes of PEMFCs in an Assembled State

Abstract

Mechanical damage to the membrane of the electrode assembly (MEA) in a proton electrolyte membrane fuel cell (PEMFC) is one of the main factors influencing its durability. In this study, a two-dimensional finite-element model is developed for a metal bipolar plate stack. We focus on studying the stress concentration phenomenon in the MEA of a PEMFC containing complete sealing components in an assembled state by considering the factors of assembly load, sealing structure, and sealing material. The results indicate that stresses are clearly concentrated in the area of the membrane under the edge of the rib of the bipolar plate on both sides of the sealing structure. Even if the average pressure on the MEA is only 0.43 MPa, the local stress is greater than 6 MPa, potentially leading to the plastic deformation of the membrane. At the joint between the frame and gas diffusion layer, the shear stress on the membrane is unusually high. Optimally designing the sealing structure, including a suitable layout of the joint, the selection of the ration of the sealing gasket height to the sealing groove depth, and the selection of the frame with material properties close to those of the membrane, will alleviate the stress concentration effectively.