Design of Large-Displacement Compliant Joints

Abstract

Flexure joints are widely used to approximate the function of traditional mechanical joints, while offering the benefits of high precision, long life, and ease of manufacture. This paper investigates and catalogs the drawbacks of typical flexure connectors and presents several new designs for highly-effective, kinematically-behaved compliant joints. A revolute and a translational compliant joint are proposed (Figure 1), both of which offer great improvements over existing flexures in the qualities of (1) large range of motion, (2) minimal axis drift, (3) increased off-axis stiffness, and (4) reduced stress-concentrations. Analytic stiffness equations are developed for each joint and parametric computer models are used to verify their superior stiffness properties. A catalog of design charts based on the parametric models is also presented, allowing for rapid sizing of the joints for custom performance. Finally, two multi-degree-of-freedom joints are proposed as modifications to the revolute joint. These include a compliant universal joint and a compliant spherical joint, both designed to provide high degrees of compliance in the desired direction of motion and high stiffness in other directions.

A rotary flexural bearing for micromanufacturing

“…Straight flexures can effectively suppress the stress concentration [7], which in turn provides more compliance and longer fatigue life at the material endurance limit. Furthermore, the straight flexures can be small in thickness but large in other dimensions for high compliance in the rotational direction and high stiffness in the other directions.…”

Kinetostatic and Dynamic Modeling of Flexure-Based Compliant Mechanisms: A Survey

“…Depending on these characteristics, flexure hinges are often designed with single or multiple axes. Notch-type flexure hinges with single axis are often profiled as rectangular section (also known as leaf spring), circular, cornerfilleted, elliptic, parabolic, hyperbolic or other conic profiles and hybrid cross sections [15,138] (see Fig. 3).…”

Definition measurement unit with flexure hinges for a wind tunnel balance

“…Research has been done on the different kind of flexure hinges and their application [6] [7] . Flexure hinges can be divided into three kinds in view of their profiles.…”