Topology optimization of leaf flexures to maximize in-plane to out-of-plane compliance ratio

Abstract

Abstract In fields requiring precision manipulation, monolithic flexures are frequently used to guide motion. They utilize the structure s predictable elastic deformation, when a force is applied, to facilitate linear and rotational motions. Amongst the several common flexure designs, leaf flexures are the best suited to ‘large’ displacement tasks. Their range is typically restricted by the actuator s supplied force, such that reducing stiffness in the motion direction beneficially increases displacement. However, high out-of-plane stiffness is required to support structural loads and reject parasitic motions. In this work, topology optimization is investigated to maximize the in-plane to out-of-plane compliance ratio of a leaf flexure. The minimization of out-of-plane compliance in leaf flexures is also investigated for comparison. In both cases, the optimized structures resemble trusses. Compliance ratio optimized structures offer performance 1.5 to 6 times greater than standard leaf structures, with reduced mass. From the results, a parameterized flexure design is suggested, which can replace leaf flexures in 3D printed mechanisms. A parallelogram linear flexure guide is analyzed as an example of a practical implementation of the optimized design.