Thermally induced vibration and strength failure analysis of thermoelectric generators

Abstract

Thermal vibration and the strength failure of a thermoelectric generator (TEG) subjected to the time-dependent heat flux is discussed in this paper. The heat flux is considered as varying along the circumference of the circular cross section of the TEG, which consists a series of n-type and p-type thermoelectric elements. Vibrations that are parallel and perpendicular to the gravity direction are analyzed, respectively. Analytical and simplified solutions of the vibration deflections of the TEG are given. The maximum principal stress in the TEG is derived analytically. Based on the criterion of maximum principal stress, the envelop curve of heat flux and electric current density corresponding to failure strength of the TEG is obtained. It is found that the vibration deflection is proportional to the heat flux and the value of square electric current. The thermal vibration reduces the output power of the TEG but it only has effect on the output power in a very short time. A bigger damping ration results in a smaller maximum principal stress. The maximum principal stress does not vary with the damping ratio if the length of TEG is small. The critical heat flux and electric current density increase and finally trend to constants with damping ratio.