Minimizing thermally induced interfacial shearing stress in a thermoelectric module with low fractional area coverage

High temperature differences between the ceramic parts in thermo-electric modules (TEMs) intended for high temperature applications makes the TEMs vulnerable to the elevated thermal stress leading to possible structural (mechanical) failures. The problem of reducing the interfacial shearing stress in a TEM structure is addressed using analytical and finite-element-analysis (FEA) modeling. The maximum shearing stress occurring at the ends of the peripheral legs (and supposedly responsible for the structural robustness of the assembly) is calculated for different leg sizes. Good agreement between the analytical and FEA predictions has been found. It is concluded that the shearing stress can be effectively reduced by using thinner (smaller fractional area coverage) and longer (in the through thickness direction of the module) legs and compliant interfacial materials.