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Project 2 nd 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
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Project 2nd UpdateAnalysis 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 Link • 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