Compressive Energy Dissipation Effects on Nonuniform Deformation and Material Conductance of Inhomogeneous Anisotropic Fibrous Porous Transport Layers

초록

Statistical numerical modeling is conducted to predict the microscopic nonuniform mechanical deformation of anisotropic fibrous porous transport layers (PTLs) under external compression. PTLs are constructed using randomly distributed carbon fibers and polytetrafluoroethylene. The porous structure is morphologically characterized as a compression-energy-dissipating medium, and energy dissipation mechanisms are implemented using Winkler’s foundation theory. The mechanical model is validated against published experimental data with nonlinear stress–strain deformation. Subsequently, extensive deformation simulations are performed to determine the mechanical characteristics of the fibrous transport media and the mechanical effects on the porosity and thickness variations. Results show that dense fiber configuration with low porosity converts more compression energy into deformation energy, thereby decreasing the energy transmission to the next contacting layers. Additionally, the bulk thickness variation of the PTLs is inversely proportional to the number of stacked layers, which suggests a potential risk of poor statistical reliability in deformation as the GDL becomes thinner, attributed to the poor thickness uniformity of the PTLs Finally, the in‒plane electrical and thermal conductances are higher than the through‒plane electrical and thermal conductances, aligning with the distribution of carbon fibers in the plane direction due to bending deformation. This study extends conventional PTL modeling, which typically focuses on the manufactured state without external compression effects, to the actual application where the PTL is compressed in an assembled state.

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