Microstructure size-dependent contact behavior of a thermoelectric film bonded to an elastic substrate with couple stress theory

Abstract

Thermoelectric films linked to elastic substrates are typical engineering structures and have applications in heat recovery systems. This article uses the nonlocal heat conduction and couple stress theory to investigate the electric-thermal-elastic behavior of the thermoelectric film placed on the elastic half-plane. The internal characteristic lengths of both the thermoelectric film and the elastic substrate are introduced to reveal the scale effects. The coupling governing integro-differential equations in terms of the interface shear stress and tensile stress are derived for the thermoelectric film and the elastic substrate. The numerical results show how the distribution of the tensile and shear stress intensity factors is affected by the stiffness ratio of the substrate to the thermoelectric film, the internal characteristic lengths of the thermoelectric film and the elastic substrate, and the thickness to length ratio of the thermoelectric film. Compared with the classical model for a thicker thermoelectric film and stiffer elastic substrate, the present study demonstrates the necessity of taking into account the microstructure lengths of the thermoelectric film and the elastic substrate.