Project 2nd Update 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 3 dimensional format

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 FEA Toggle Mechanism Calculations For both analysis the same configuration will be utilized The linkage is comprised of two links, a slide, and a stop The links and slide are connected by pins Link Slide Stop

Methodology for the FEA Toggle Mechanism Calculations Cont. The stop allows for the analysis to modify the compliant material portion of the toggle mechanism Linear elements with incompatible modes are used throughout the analysis Mesh sensitivity studies will be performed

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