Creep constitutive law prediction via short-term evaluation using a small size testing method

Abstract

To efficiently assess the mechanical reliability and long-term durability of solid oxide fuel cells (SOFCs) and solid oxide electrolyser cells (SOECs), a suitable creep test method and prediction of the material response is necessary. This study investigates the effectiveness of the small punch (SP) testing method for Ni–YSZ composites and in rapidly determining the constitutive creep law for SOFC materials. The creep properties of Ni–YSZ composites are evaluated under a 1% H2 environment at temperatures of 800–900 °C and stresses of 36–58 MPa. The finite element method is used to simulate the SP tests and generate numerical creep curves. These curves are fitted to the experimental curves to obtain the parameter set in the creep constitutive law of the strain hardening model. The numerical and experimental creep curves are well-fitted with only a 0.44% difference and convergent parameter sets equal to C1=1.0× 10−12, C2=1.03, C3 = -1.70, C4=96.78 in the strain hardening law, indicating the usefulness of the SP method and creep constitutive law for characterising and predicting the creep properties of SOFC constituent materials. This study highlights the importance of accurate characterisation of creep properties for predicting the long-term performance and reliability of SOFCs.