  Under typical PEM fuel cell operating conditions, part of membrane electrode
assembly is subjected to humidity cycling due to variation of inlet gas RH
and/or flow rate. Cyclic membrane hydration/dehydration would cause cyclic
swelling/shrinking of the unconstrained membrane. In a constrained membrane, it
causes cyclic stress resulting in mechanical failure in the area adjacent to
the gas inlet. A mathematical modeling framework for prediction of the lifetime
of a PEM FC membrane subjected to hydration cycling is developed in this paper.
The model predicts membrane lifetime as a function of RH cycling amplitude and
membrane mechanical properties. The modeling framework consists of three model
components: a fuel cell RH distribution model, a hydration/dehydration induced
stress model that predicts stress distribution in the membrane, and a damage
accrual model that predicts membrane life-time. Short descriptions of the model
components along with overall framework are presented in the paper. The model
was used for lifetime prediction of a GORE-SELECT membrane.
