Compliant Mechanism Synthesis Using Nonlinear Elastic Topology Optimization with Variable Boundary Conditions

TL;DR

This paper introduces an automated method for optimizing boundary conditions and material layout in compliant mechanism design, significantly improving performance by leveraging nonlinear elastic physics and eliminating manual boundary placement.

Contribution

It develops a novel approach that simultaneously optimizes boundary conditions and material distribution in topology optimization of compliant mechanisms using nonlinear elasticity.

Findings

Performance improvements of 47%-380% over previous designs.

Automated boundary placement enhances mechanism performance.

Nonlinear elastic physics enables synthesis of mechanisms with large displacements.

Abstract

In topology optimization of compliant mechanisms, the specific placement of boundary conditions strongly affects the resulting material distribution and performance of the design. At the same time, the most effective locations of the loads and supports are often difficult to find manually. This substantially limits topology optimization's effectiveness for many mechanism design problems. We remove this limitation by developing a method which automatically determines optimal positioning of a prescribed input displacement and a set of supports simultaneously with an optimal material layout. Using nonlinear elastic physics, we synthesize a variety of compliant mechanisms with large output displacements, snap-through responses, and prescribed output paths, producing designs with significantly improved performance in every case tested. Compared to optimal designs generated using best-guess boundary conditions used in previous studies, the mechanisms presented in this paper see performance increases ranging from 47%-380%. The results show that nonlinear mechanism responses may be particularly sensitive to boundary condition locations and that effective placements can be difficult to find without an automated method.