A Method for the Design of Compliant Mechanisms With Small-Length Flexural Pivots

Abstract

Compliant or flexible-link mechanisms gain some or all of their motion from the relative flexibility of their joints rather than from rigid-body joints only. Unlike rigid-body mechanisms, energy is not conserved between the input and output ports of compliant mechanisms because of energy storage in the flexible members. This effect and the nonlinearities introduced by large deflections complicate the analysis of such mechanisms. The design of compliant mechanisms in industry is currently accomplished by expensive trial and error methods. This paper introduces a method to aid in the design of a class of compliant mechanisms wherein the flexible sections (flexural pivots) are small in length compared to the relatively rigid sections. The method includes a definition and use of a pseudo-rigid-body model, and the use of a large-deflection finite element type algorithm. An example is used to illustrate the design technique described.

New empirical stiffness equations for corner-filleted flexure hinges

“…In the early work of Howell and Midha (1994), they presented a computer-aided design method to pseudo-rigid-body model that included short length beam. A short length beam can be considered as a corner-filleted flexure hinges without filleted corners at the junction of flexible part and rigid part.…”

A monolithic compliant large-range gravity balancer

“…Alternative design methods have been developed over the past decades, and a majority of designers have found their way to lumped parameter models like, e.g. pseudo-rigid-body models (PRBM) [2] [3] [4], in order to deal with these challenges, but compromising in terms of accuracy, freedom of shape, and moreover often basing their designs on equivalent rigid body mechanism designs.…”

Level set based method for design of compliant mechanisms

“…There are essentially two classes of numerical methods for the design of compliant mechanisms: the kinematic synthesis approach based on the traditional rigid-body kinematics ( (Howell et al,, 1994), (Howell" 2001)) and the topology optimization method for continuum structures ( (Ananthasuresh et al,, 1994), (Frecker et al,, 1997), (Sigmund" 1997)). The method proposed in this work belongs to the second category.…”