A multiphysics equivalent stiffness model of a PEMFC integrating the nonlinear mechanical behaviour of cell components

Proton Exchange Membrane Fuel Cells (PEMFCs) couple electrochemical, thermal and mechanical phenomena, making stack-level mechanical prediction challenging yet critical for design. This study introduces an Equivalent Stiffness Model (ESM), capable of rapid multiphysics simulations, that originally incorporates the nonlinear mechanical properties of cell components by employing established constitutive models from the literature. By integrating iterative techniques, the model continuously updates the equivalent stiffness of the elements. Moreover, it allows for the selection of various materials, components, and operating conditions for any simulation, thereby linking the properties of individual components to the overall mechanical behaviour of the stack and permitting the evaluation of different stack configurations. It calculates component scale and overall system deformation, accounting for thermal-induced expansions. Validation against a published configuration shows close agreement in stack stiffness and displacement, supporting the use of the ESM as a flexible tool for preliminary PEMFC stack design.