Meso-scale stress response of thin ceramic membranes with honeycomb support
Planar solid oxide fuel cells are made up of repeating sequences of electrolytes, electrodes, seals, and current collectors. For electrochemical reasons it is best to keep the electrolyte as thin as possible. However, for electrolyte-supported cells, the thin electrolytes are susceptible to damage during production, assembly, and operation. One of the latest generation electrolytes employs a meso-scale honeycomb layer to support thin, electrochemically efficient membranes. Using finite element analysis, a two-scale model computes distributions of first principal stresses throughout a representative unit cell of the meso-scale structure. Displacement at the macro-scale is informed by meso-scale geometry via a homogenized equivalent stiffness, while the stresses at the two scales are related via a scalar magnification factor. The magnification factor is computed for a variety of geometries and loading conditions. Physical specimens are measured in tension to obtain an experimental magnification factor which agrees well with the simulations. When both the stiffness and magnification factor for a given meso-scale pattern are known, the macro-scale geometry can be analyzed without revisiting the meso-scale model, thus reducing computational time and costs.
KeywordsThin ceramic membranes Honeycomb support Solid oxide fuel cell Meso-scale finite element simulation Stress magnification
This work was supported by the Ohio Department of Development’s Third Frontier Fuel Cell Program. The authors would also like to thank the staff of NexTech Materials Ltd. for many helpful discussions concerning electrolyte materials and geometries.
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