Keywords

compliant mechanism, compound flexures, center shift reduction

Abstract

Because compliant mechanisms achieve their motion through deflection of flexible members, they have a limited range of motion and finite stiffness. Many common flexure geometries also suffer from a non-stationary center of rotation. These properties can be obstacles to their adoption in applications that require large displacements, low stiffness, or stationary centers of rotation. This work presents the concept of compound flexures: by assembling arrays of flexures, we can increase range of motion, decrease stiffness, and reduce center shift. We first develop the theory behind some of the basic behavior of compound joints. Then finite element analysis is used to explore other aspects of compound joint behavior such as off-axis stiffness and quantifying the center shift for two flexure types when used in compound joints of various configurations. It is shown in an example that range of motion can be doubled with no appreciable loss in off-axis stiffness, while the desired stiffness κθz remains unchanged. A method is presented to achieve zero center shift for a specified rotational displacement. Compound joints are shown to exhibit greater ranges of motion, higher off-axis stiffness, and reduced center shift compared to traditional joints. Keywords: compliant mechanism, compound joint, center shift, cross-axis-flexural pivot, cartwheel flexure

Original Publication Citation

Merriam, E., Lund, J.M., Howell, L.L., “Compound Joints: Behavior and Benefits of Flexure Arrays,” Precision Engineering, Vol. 45, pp. 79-89, DOI:10.1016/j.precisioneng.2016.01.011, 2016.

Document Type

Peer-Reviewed Article

Publication Date

2016

Publisher

Precision Engineering

Language

English

College

Ira A. Fulton College of Engineering

Department

Mechanical Engineering

University Standing at Time of Publication

Full Professor

Download

Share

COinS