  An analytical model of mechanical stress in a polymer electrolyte membrane
(PEM) of a hydrogen/air fuel cell with porous Water Transfer Plates (WTP) is
developed in this work. The model considers a mechanical stress in the membrane
is a result of the cell load cycling under constant oxygen utilization. The
load cycling causes the cycling of the inlet gas flow rate, which results in
the membrane hydration/dehydration close to the gas inlet.
Hydration/dehydration of the membrane leads to membrane swelling/shrinking,
which causes mechanical stress in the constrained membrane. Mechanical stress
results in through-plane crack formation. Thereby, the mechanical stress in the
membrane causes mechanical failure of the membrane, limiting fuel cell
lifetime. The model predicts the stress in the membrane as a function of the
cell geometry, membrane material properties and operation conditions. The model
was applied for stress calculation in GORE-SELECT.
