Design of Monolithic Compliant Mechanisms for Microactuator Using Topology Optimization Schemes

Micro-compliant mechanisms in this paper refer to the mechanical parts of micro-actuators which generally coupled with piezoelectric materials in micro-systems. A novel multi-objective programming methodology for the design of monolithic compliant mechanisms has been presented by using topology optimization schemes, in which mechanical flexibility and structural stiffness are both considered as the optimization objectives. The compliant mechanisms developed in this way can not only provide the desired output displacement but also the sufficient stiffness to resist the reaction force and maintain its shape when holding the work-piece. SIMP interpolation scheme, introduced to relax the original optimization problem with large amounts of discretized variables, is applied to indicate the dependence between material modulus and the pseudo-element densities. In addition, a density filtering approach is presented to prevent the numerical singularities, such as checkerboards, mesh-dependency and one-node connected hinges in resulting mechanisms. The method of moving asymptotes classified to the sequential convex programming methods is applied to solve the optimization problem. The validation of the methods presented in this paper is substantiated by a typical application.