Sparse Monolithic Compliant Mechanisms Using Continuum Structural Topology Optimization

A formulation for design of continuous, hinge-free compliant mechanisms is developed and examined within a continuum structural topology optimization framework. The proposed formulation involves solving two nested optimization problems. In the inner problem the arrangement of a constrained amount of structural material is optimized to maximize the mechanism’s mutual potential energy in response to a force loading at the input port while working against artificial springs on the input and output ports. As the relative stiffness of the artificial springs increases, the material continuity of the mechanism also increases to the point where de facto “hinge” regions are eliminated. In the outer problem, one solves for an appropriate amount of structural material that yields the desired compliance characteristics of the mechanism when working against the workpiece resistance. Different aspects of the proposed formulation are demonstrated on a number of examples and discussed.