Continuum Approach for Modeling Mechanical Fatigue of Ionomer Membrane

The mechanical degradation of the proton exchange membrane is one of the main aspects affecting the lifetime of proton exchange membrane fuel cell. In previous study, we have found a plastic deformation occurs after the temperature and water content are increased, and would be substantially enhanced by the gas pressure difference between the anode and cathode. We further concentrates on the stress/strain evolution in the membrane of fuel cells throughout the assembly and running processes. However, the polymer electrolyte membranes suffers complex hygrothermal loading in the running process and show unlinear visco-elastic–plastic behavior. Thus the membrane express a different fatigue behavior compared to traditional metal materials. We propose an approach suitable for modeling mechanical degradation in polymer electrolyte membranes based on a constitutive model of Nafion membrane considering the rate, temperature, and hydration dependent deformation response under cyclic loading. A finite element analysis was performed and the results were compared to experimental observations.