Topology design of compliant mechanisms with stress constraints based on the topological derivative concept

Compliant mechanisms are mechanical devices composed by one single piece that transforms simple inputs into complex movements. This kind of multi-flexible structure can be manufactured at a very small scale. Therefore, the spectrum of applications of such microtools has become broader in recent years including microsurgery, nanotechnology processing, among others. In this paper, we deal with topology design of compliant mechanisms under von Mises stress constraints. The topology optimization problem is addressed with an efficient approach based on the topological derivative concept and a level-set domain representation method. The resulting topology optimization algorithm is remarkably efficient and of simple computational implementation. Finally, some numerical experiments are presented, showing that the proposed approach naturally avoids the undesirable flexible joints (hinges) by keeping the stress level under control.