The Nafion® proton exchange membrane is regarded as the core component of a fuel cell. Any influences on its physical properties, mechanical behavior, or structural integrity can greatly affect the fuel cell's overall performance. Nafion®'s properties are highly responsive to environmental factors such as temperature and humidity, shifting its mechanical behavior from rubbery to glassy. During operation, Nafion®, being hydrophilic, absorbs water, leading to swelling and internal stresses. Over time, the combination of swelling, thermal loads, and chemical aging causes significant damage, especially under hydration-dehydration cycles.

 This research focuses on the thermo-chemico-mechanical degradation of the membrane during hydration-dehydration cycles and its impact on fuel cell performance. A specialized framework is developed to model water diffusion through Nafion® under varying humidity. Additionally, a mechanical model is used to calculate the plastic deformation from swelling, helping to estimate the enlargement of pinholes. Properties like Young’s modulus and yield stress are analyzed for their sensitivity to humidity and temperature. The framework also incorporates chemical degradation and examines its effect on damage evolution.

 Parametric analysis under cyclic hygro-thermal loading examines the evolution of damage and fuel cell performance relative to humidity, temperature and time. This model accurately predicts damage and plasticity in Nafion® membranes under operational conditions, distinctly quantifying the contributions of mechanical, thermal, and chemical aging to performance degradation. This offers a comprehensive analysis often missing in existing studies.