Sequential topology and shape optimization framework to design compliant mechanisms with boundary stress constraints

Abstract

We present a sequential topology and shape optimization framework to design compliant mechanisms with boundary stress constraints. In our approach, a density based topology optimization method is used to generate the configuration of the mechanisms. Afterward, a node based shape optimization is invoked to obtain an exact boundary representation. A specialized, optimality criteria based design update is formulated for the shape optimization. To avoid impractical hinges with point connections, stress constraints are imposed. The stress constraints are imposed using two strategies: Local stress constraints on the nodes of the boundary or global P-norm stress constraints in the domain. Further, an adaptive shape refinement strategy is adopted to increase the design space of shape optimization and to capture the finescale details of the geometry. Finally, numerical experiments are presented, showing that the proposed approach can be effectively applied to the design of compliant mechanisms with stress constraints.