Metallic bipolar plates are desirable for the automotive applications of PEMFCs because they offer excellent mechanical properties over the graphite-based bipolar plates. The flow channel configuration using metallic bipolar plates also enhances a stack’s power density. Modeling and simulation of the mechanical behavior of metallic bipolar plates under compression and the impact of mechanical stress-strain on the transport/electrochemical reactions in the membrane electrode assembly (MEA) are reported in this paper. A two-dimensional MEA model with metallic bipolar plates is developed. A two-stage approach with one-way coupling is employed to study the effects of mechanical stress-strain on transport/electrochemistry, namely, solid mechanics of the model is first solved, followed by the solution of coupled heat and mass transport over the deformed geometry obtained from the solid mechanics solution. The transport equations solved include the conservation of mass, species/charged species, and energy. Transport properties such as the porosity, permeability and contact resistance of the MEA components are either obtained from published works or expressed as functions of strain in the model, which are derived from numerical reconstruction of the materials. Furthermore, membrane degradation reactions are modeled as a function of stress to gain insight to the mechano-chemical coupling in the MEA. The comprehensive model was solved using Multiphysics COMSOL software v.5.3.

Figure 1 shows the model with typical distributions of von Mises stress over the computational domain (note different scales of stress in the bipolar plates and the MEA), which are obtained by solving solid mechanics of the model. The stress and strain information of the solid mechanics solution as well as the deformed geometry are subsequently passed to the coupled heat and mass transport solution procedure to compute the distributions of species, potentials, and temperature. The present model establishes a platform to numerically investigate the interplay between mechanical responses and transport/electrochemistry in the MEA.