Design of multiphysics actuators using topology optimization - Part II: Two-material structures

This is the second part of a two-paper description of the topology optimiza tion method applied to the design of multiphysics actuators and electrother momechanical systems in particular. The first paper is focussed on one-mate rial structures, the second on two-material structures. The extensions of t he topology optimization method in this part include design descriptions fo r two-material structures, constitutive modelling of elements with mixtures of two materials, formulation of optimization problems with multiple const raints and multiple materials and a mesh-independency scheme for two-materi al structures. The application in mind is the design of thermally and elect ro thermally driven micro actuators for use in MicroElectroMechanical Syste ms (MEMS). MEMS are microscopic mechanical systems coupled with electrical circuits. MEMS are fabricated using techniques known from the semi-conducto r industry. Several of the examples from Part I are repeated, allowing for the introduction of a second material in the design domain. The second mate rial can differ in mechanical properties such as Young's modulus or electri cal and thermal conductivity. In some cases there are significant gains in introducing a second material. However, the gains depend on boundary condit ions and relations between the material properties and are in many cases in significant. (C) 2001 Elsevier Science B.V. All rights reserved.