PNNL

Abstract

Crack deflection and penetration paths at interfaces of the multilayer structures in a solid oxide fuel cell (SOFC) under thermomechanical loading are predicted. An asymptotic approach was applied to a three layer structure typical of an SOFC unit cell consisting of the anode, electrolyte and cathode. Residual thermal stress due to thermal cycling during operation of the fuel cell was taken into consideration for the crack propagation path prediction. Finite element analysis was utilized to determine the energy release rate and possible crack propagation paths. Influence of thermal and mechanical loads on crack propagation paths was compared. An energy criterion as a function of crack length was used for the prediction of possible crack extension, and an analysis of the influence of crack length on the crack propagation path is presented. This work on prediction of crack propagation paths in SOFC materials, based on thermomechanical properties and geometry, will provide a powerful tool for guidance on how to tailor gradient porous microstructures of electrodes to improve toughness and performance of fuel cell components.