Design of Compliant Mechanisms Using a Pseudo-Rigid-Body Model Based Topology Optimization Method

Abstract

This paper presents a novel method for the topological synthesis of flexure-based compliant mechanisms. Such kind of mechanisms are usually obtained by replacing the kinematic pairs of existing rigid-body mechanisms with flexure hinges, which is often regarded as the rigid-body replacement approach. This approach uses the topologies from rigid-body mechanism and pays little attention to the selection of the optimal topology among them. The proposed method tries to find out the optimal topology directly from design problem, without referencing to the existing rigid-body mechanisms. The topology of the flexure-based compliant mechanisms is represented by the pseudo-rigid-body model (PRBM). The PRBM is expressed in a ground structure using an adjacency matrix. An analysis method based on the principle of minimum potential energy is introduced to evaluate the static performance of the PRBM candidates quantitatively. Using genetic algorithm (GA), the optimal PRBM can be found out according to the objective function that is based on the analysis results. The validity of the proposed method is tested on a single-input-output compliant mechanism design problem.