0
Research Papers

Development of Criteria for Lamina Emergent Mechanism Flexures With Specific Application to Metals

[+] Author and Article Information
Devin B. Ferrell

Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602devin.ferrell@gmail.com

Yanal F. Isaac

Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602issac.yanal@gmail.com

Spencer P. Magleby1

Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602magleby@byu.com

Larry L. Howell

Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602lhowell@byu.com

1

Corresponding author.

J. Mech. Des 133(3), 031009 (Mar 10, 2011) (9 pages) doi:10.1115/1.4003538 History: Received May 22, 2010; Revised January 12, 2011; Published March 10, 2011; Online March 10, 2011

This paper develops new design criteria for lamina emergent mechanism (LEM) flexures with particular application to sheet-metal-formed metal flexures. The LEM flexure design criteria are based on the relative performance between the LEM flexure and a section of lamina that is of the same overall length, width, and thickness as the LEM flexure. Novel metal revolute and torsional LEM flexures are presented and evaluated against the LEM flexure design criteria. Both flexures meet the proposed criteria, and their performance is evaluated in the design of a basic crank-slider mechanism. When compared with unformed flexures of the same dimensions, the revolute and torsional metal LEM flexures are found to improve the crank-slider performance.

Copyright © 2011 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Example of a 4 bar lamina emergent mechanism with lamina emergent torsional flexures

Grahic Jump Location
Figure 2

Examples of how sheet metal forming processes can be used to (a) decrease width, (b) decrease thickness, and (c) increase length to form a LEM flexure

Grahic Jump Location
Figure 3

Examples of how sheet metal forming process can be used to increase off-axis stiffness through changing the cross-sectional profile of the benchmark

Grahic Jump Location
Figure 4

The LEM flexure (below) is the same overall length L, width b, and thickness h as the performance datum geometry or benchmark (top)

Grahic Jump Location
Figure 5

Example of (a) a LEM member providing distributed out-of-plane motion under bending load and (b) a LEM flexure providing localized out-of-plane motion under the same bending load as in (a)

Grahic Jump Location
Figure 6

RUFF flexure joint in (a) deflected and (b) undeflected positions

Grahic Jump Location
Figure 7

Schematic of post-formed RUFF

Grahic Jump Location
Figure 8

Schematic of RUFF fabrication setup

Grahic Jump Location
Figure 9

Both the undeflected and deflected positions of the full RUFF closed-form model

Grahic Jump Location
Figure 10

Schematic of the force-deflection tester used to determine the stiffness characteristics of the RUFF prototype

Grahic Jump Location
Figure 11

Photographs of (a) the RUFF prototype and (b) the RUFF prototype deflected in the force-deflection tester

Grahic Jump Location
Figure 12

Force-deflection plot of the RUFF closed-form solution, FEA simulation, and prototype test data along with a force-deflection plot of the benchmark. The vertical dotted lines emphasize the point at which the maximum equivalent stress (σmax) equals the material yield stress (σyield).

Grahic Jump Location
Figure 13

Force-deflection plot of nondimensionalized RUFF data

Grahic Jump Location
Figure 14

Representation of desired (moment Mz) and undesired (torsion Tx) loading shown on both the (a) benchmark and the (b) RUFF

Grahic Jump Location
Figure 15

Comparison of off-axis stiffness ratio between the RUFF and benchmark

Grahic Jump Location
Figure 16

TUFF flexure joint in (a) deflected and (b) undeflected positions

Grahic Jump Location
Figure 17

FEA deformation plot of TUFF rotated 45 deg under end torque

Grahic Jump Location
Figure 18

FEA equivalent stress plot of TUFF displaced through 45 deg of rotation

Grahic Jump Location
Figure 19

Schematic of torque-rotation tester setup used to determine the stiffness characteristics of the TUFF prototype

Grahic Jump Location
Figure 20

Photographs of (a) the TUFF prototype and (b) the TUFF prototype deflected in the torque-rotation tester

Grahic Jump Location
Figure 21

Torque-rotation plot of the TUFF FEA simulation and prototype test data along with a torque-rotation plot of the benchmark. The vertical dotted lines emphasize the point at which the maximum stress (σmax) in the LEM profile or TUFF has reached the material yield stress (σyield).

Grahic Jump Location
Figure 22

Representation of undesired (Mz) and desired (Tx) loading shown on both the (a) benchmark and the (b) TUFF

Grahic Jump Location
Figure 23

Off-axis stiffness comparison of the TUFF and benchmark

Grahic Jump Location
Figure 24

LET joint (6) (top) compared with the compound LET joint (bottom), which replaces the LET members in torsion with TUFFs and the LET members in bending with RUFFs

Grahic Jump Location
Figure 25

Schematic of the rigid-body equivalent design

Grahic Jump Location
Figure 26

Renderings of the (a) undeflected and (b) deflected FEA models of the RUFF and TUFF crank-slider, as well as photographs of the RUFF and TUFF crank-slider prototypes in both the (c) undeflected and (d) deflected positions

Grahic Jump Location
Figure 27

Comparision plot of the stress behavior for both the LEM crank-slider with standard LET joints and the LEM crank-slider with compound RUFF and TUFF LET joints as φ increases

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In