Thermal Residual Stress and Failure Probability of Functionally Grade Ni-YSZ Anode of Solid Oxide Fuel Cells Using a Finite Element Analysis

The differences of thermal expansion coefficient between the components in the solid oxide fuel cells (SOFCs) is one of the important causes of large residual thermal stress in the fabrication process of the cell. The functionally graded (FG) Ni-YSZ anode design was introduced between Ni-YSZ support and YSZ electrolyte. Residual thermal stress was calculated by finite element method (FEM) using the commercial ANSYS package. Weibull probability model was used to evaluate the failure probability. The effects of sublayer number w, exponential factor n, and gradient layer thickness on the stress and failure probability are discussed. The calculation results show that the FG anode layer can obviously reduce the stress. The failure probability can be reduced by several orders of magnitude at most as compared with the conventional SOFC. The sublayers number w =2 is a suitable value. The research provides a reference for further optimizing the stress in SOFC.