Transcript First Project Update.pptx

Project Proposal
Analysis of a Toggle Mechanism:
Sensitivity to Link Sizes and
Compliance Material
By: Joseph Hughes
MANE 6980
Toggle Mechanism Finite Element Analysis
Was Divided into Two Sections
 Sensitivity to Linkage Length
 Use varying length of linkages to model potential
machining tolerances and their impacts on the stresses
within the linkage
 Sensitivity to Compliant Material
 Vary the compliant material element within the linkage
to determine their impact on the stresses within the
linkage
 This analysis will be performed in a 2 dimensional
format as the stress is not expected to change
through the thickness of the components
Force Within Over-Toggle Mechanism Is Sensitive
To Link Length
 To model the toggle mechanism as it passes the toggle point,
the adjacent links are allowed to rotate about their end points
as the connecting pin is moved vertically downward
 The linkage lengths are varied throughout the analysis to
determine the impact to the stress within the links
 The linkage lengths could change within a toggle mechanism
due to factor such as manufacturing tolerances
 FEA models of the linkage have been created but the analysis is
not yet complete
Force Within Over-Toggle Mechanism Is
Sensitive To Compliant Material Choice
 Various compliant materials will be evaluated within the
linkage
 Neoprene Rubber – Often used within toggle clamps
 Natural Rubber – Used in many applications and has lower
stiffness than Neoprene
 Beryllium Copper – Material commonly used in springs
 Various thicknesses of the compliant material will also be
evaluated
 Rubbers tend to behave in a non-linear fashion and their
stiffness depends on things like shape factor
Methodology for the Toggle Mechanism
Calculations
Stress Within The Adjacent Links Is Expected
To Change With Modification To Mechanism
 The stress within the adjacent links is expected to increase
with increase in:
 Adjacent link length, as it would cause more compression within
adjacent links
 Stiffness of compliant material, as more stress will be transferred
into the adjacent links
 The stress in the adjacent links is expected to decrease with:
 Increase in thickness of the compliant material, as it allows more
compression of the compliant material with less force within the
adjacent links
 Decrease in stiffness of the compliant material, as it allows more
compression of the compliant material with less force within the
adjacent links
References Will Be Used Throughout The Analysis
 (1) Avallone, Eugene; Baumelster, Theodore; Sadegh, Al; Mark’s
Standard Handbook for Mechanical Engineers; McGraw Hill; dated
November 2006
 (2) Oberg; McCauley, Christopher; Ryffel, Henry; Holbrook Horton;
Jones, Franklin; Machinery’s Handbook 28th Edition, Industrial Press,
Inc.; dated February 2008
 (3) Brooks, Scott; Halverson, Peter; Howell, Larry; Magleby, Spencer;
Type Synthesis of Compliant 5-Bar Mechanisms With Application to
Mechanical Disc Brakes. Mechanical Engineering Department,
Brigham Young University, Utah, USA. NaCoMM-2007-103
 (4) Tso, Pei-Lum. The Kinematic Synthesis of Toggle Clamps. Journal
of Manufacturing Science and Engineering, August 1998, Volume 120,
Issue 3, 648