Preliminary Investigations Into the Design and Manufacturing of Fully Compliant Layered Mechanisms (FCLMs)

Abstract

The relatively new technology of additive manufacturing (also known as “3-D printing” or “rapid prototyping”) presents some intriguing possibilities for the design of compliant mechanisms. This paper introduces a new category of compliant mechanisms — Fully Compliant Layered Mechanisms (FCLMs) — that rely on additive manufacturing to produce mechanisms with complex geometry. An FCLM is a fully compliant mechanism whose geometry requires two or more links to cross over one another to achieve a desired motion. The need to have crossing links requires the mechanism to have multiple layers. Such a mechanism is fairly easy to produce using additive manufacturing systems, but the more brittle materials associated with additive manufacturing also impose some limitations on the design of FCLMs. This paper presents an overview of some of these limitations along with approaches that are being developed to solve the challenges of using additive manufacturing in the production of compliant linkages. The focus is on lumped compliant mechanisms with key challenges that include: the selection of a proper joint type; the layering of the compliant mechanism; and the stability of the mechanism. Beam type joints such as a spiral joint are found to be suitable for use with additive manufacturing. These joints have some lateral instability which can be reduced by proper layering and structural reinforcements in the mechanism. These joints also pose the potential for increased parasitic motion, which can be minimized by joint design approaches. Preliminary ideas are presented for the solution of these problems along with some needs for future development.