Evolutionary optimization of compliant mechanisms subjected to non-uniform thermal effects

Abstract

In this research, an evolutionary optimization procedure is proposed for the design of compliant thermal microactuators subjected to non-uniform temperature fields. Compliant micro-mechanisms that are responsible for movement play a crucial role in MEMS design, which cannot be manufactured using typical assembly processes and may not make use of traditional hinges or bearings. During the past decades topology optimization techniques have been shown to be efficient tools to conceive these kinds of distributed compliant mechanisms. The procedure applied in this paper is based in the evolutionary structural optimization (ESO) method, which has been successfully applied to several optimum material distribution problems but not for non-uniformly heated compliant mechanisms including conduction and convection effects. In previous works, this group has successfully applied this method for compliant mechanism optimization under directly applied input loads and under simple uniform temperature fields. The present paper aims to progress on this work line developing an extension of this procedure, based on an additive version of the method, to approach the more complicated case of non-uniformly heated thermal microactuators. The validity of this technique is demonstrated in several examples and the designs obtained are compared favourably with the analytical solutions and with results by other methods. Future works will be based on electro-thermal actuation and non-uniform Joule heating will be considered as well, which lead to more elegant and real solutions.