In this video, AltaSim Technologies shows you how to simulate Thermal-Structure Interaction in a MEMS energy harvester, using COMSOL Multiphysics. The MEMS energy harvester model shown here includes a heat source in contact with the end of a bimaterial cantilever. As the layered cantilever heats up, the differential in the coefficient of thermal expansion between the two materials causes the cantilever to bend away from the heat source. The cantilever retracts back toward the heat source as it cools. Thermal cycling and the resulting mechanical deformation in an energy harvester can be converted to electricity through the pyroelectric effect.
The model implements bidirectional coupling between solid mechanics and heat transfer phenomena to accurately represent the operation of the MEMS device. This enables contact pressure and thermal expansion effects to be coupled properly to heat transfer in solids. At the end of the video you will see a transient analysis of the operating energy harvester, demonstrating the displacement of the cantilever with respect to temperature.