Design of multiphysics actuators using topology optimization - Part I: One-material structures

This is the first part of a two-paper description of the topology optimizat ion method applied to the design of multiphysics actuators and electrotherm omechanical systems in particular. The first paper is focussed on one-mater ial structures, the second on two-material structures, The extensions of th e topology optimization method in this first part include coupled and non-l inear finite element analyses, constitutive modelling of elements with inte rmediate densities, adjoint sensitivity analyses and formulation of optimiz ation problems with multiple constraints. The application in mind is the de sign of thermally and electrothermally driven micro actuators for use in mi croelectromechanical systems (MEMS). MEMS are microscopic mechanical system s coupled with electrical circuits. MEMS are fabricated using techniques kn own from the semi-conductor industry. Examples include design of thermal an d electrothermal micro actuators with one, two and three degrees of freedom (d.o.f.). The differences between modelling and optimizing the actuators u sing linear and non-linear finite element analyses are discussed in detail. Ways for systematic interpretation and transfer of the topology optimized designs to the micromachining process are also discussed and finally, some test results prove the validity of the method. (C) 2001 Elsevier Science B. V. All rights reserved.