Thermal stress analysis of half-Heusler thermoelectric module by 3D finite element model and orthogonal tests

Irrational structural design and mismatch of material mechanical properties cause thermal stress in thermoelectric (TE) devices, which leads to performance degradation and device failure. Previous researches mainly focus on the independent impact of specific structural parameters, while the influence of material mechanical properties and coupling of multiple factors are often overlooked. In this study, a 3D finite element model was built by Abaqus to study the thermo-mechanical performance of TE devices, in which the temperature dependent material properties were considered. Through orthogonal tests, the effect of structural parameters and material properties, and their coupled impact on thermal stress were investigated. The trend and significance of the effect for these factors were obtained, and the optimized structure and material options were proposed. The variance analysis shows that the thickness of barrier layers and electrodes are most crucial among all structural parameters, while the yield strength of barrier layers, the coefficient of thermal expansion of ceramics have the most significant influence on stress among the all material properties. Moreover, the couplings between these factors cannot be ignored. Taking the ultimate strength as standard, the optimal model we proposed increase the mechanically safety operating temperature of the device from 500 K to 900 K, which provides effective guidance for thermal stress reducing and service reliability improvement of TE devices.