Structural Reliability Evaluation of Thermoelectric Generator Modules: Influence of End Conditions, Leg Geometry, Metallization, and Processing Temperatures

Abstract

Structural reliability of thermoelectric generators (TEGs) in medium to high temperature applications still remains a challenge. Currently there are no established standards for evaluating the thermomechanical reliability of TEGs during new material and module development phases in the industry. In this work we implemented a procedure for evaluating the reliability of brittle TE materials based on the common practice in the ceramics industry. The probabilistic thermomechanical reliability of TEG couples and modules is evaluated using Weibull analysis. Finite element simulations were carried out to study the influence of TEG couple parameters such as leg geometry, dimensions, spacing, metallization thickness, and processing conditions on the stresses, and the structural reliability evaluations were conducted based on the TE material stresses. Results showed that the boundary conditions and processing temperatures have significant influence on the TE material and metallization stresses and overall device reliability. The external compressive load significantly enhanced structural reliability. Results also showed that among geometrical parameters the leg length has a dominating influence on the overall stresses compared to the leg cross-sectional shapes. The cross-section geometry of legs showed considerable effect at shorter lengths, and the influence diminished with increased lengths. The proposed approach for evaluating the structural reliability could be integrated with performance optimization techniques for developing optimal and reliable TEG devices.