Custom Analysis And Design of Clutch Pedal

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Analysis And Design of Custom
   Hydraulic Clutch Pedal


                       Zachariah John
                      Henry Helfman
                   Bernadette Bautista
Previous Pedal Design
              • Uses rod and crank system
              • Requires adjustment to
              compensate clutch wear
              • Has 6 major high wear
              surfaces
              • Mechanical geometry
              (pivot points) limits
              applications
Bell Crank
                      Non-Hydraulic
                      Clutch Linkage
                      Systems
Cable Clutch System
Hydraulic Clutch System Advantages
                     1. Easy to mount master
                        cylinder on flat surface
                        behind pedal (firewall)
                     2. Few wear items which
                        have much lower wear
                        than other clutch
                        linkage systems
                     3. Piston/Cylinder
                        assemblies
                        automatically
                        compensate for clutch
                        surface wear and need
                        no adjustment
Improved Design Goals

          1. Make a system which allows
          installation of hydraulic clutch
          pedal when standard parts are
          unavailable
          2. Use mostly production or
          aftermarket parts and keep custom
          manufactured parts to a minimum
          to be cost effective and practical
          3. Use simple system that can be
          implemented to any vehicle’s
          firewall section (space permitting)
                Model Information
• The improved pedal is a modified bell
  crank unit retrofitted to operate a
  Hydraulic Master Cylinder.
• An actuation arm which joins the pedal
  to the master cylinder rod is welded to
  the original pedal.
• The pedal has a weight of 1.869 lb
  (4.8359E-03 lbm).
• Galvanized Annealed Steel is the
  material used in the pedal.
    Material Properties for
   Galvanized Annealed Steel

• Modulus of Elasticity[psi] 2.7993E+07
  Density [lbm/in^3]         7.5148E-04
  Poisson's Ratio            0.2900
  Thermal Expansion
  Coefficient [ 1/degF ]      9.8889E-06
FEA Loads & Constraints




  • Constrained and
    loaded with 20 lb
    applied load to lower
    base pedal surface
  • Analyzed with Ansys
       Analysis Specifications
• Applied Loads:
• Type            Entity       X            Y
  Force [ lb ] Area          91.56         8.010
• Force [ lb ] Area          -14.14        -14.14
• Reaction Forces [ lb ]:
•     X           Y            Z
• -76.867       -22.103     -4.12794E-04
• Total Moment [ lb-in ]:
•     X           Y           Z
     7.4646     -85.318     98.502
  Equivalent Stress, Maximum
Principal Stress and Critical Point
                 Fatigue Test
• The Critical Stress (SC) on the clutch pedal is
  24.750 ksi.
• 108 Cycle Strength (endurance limit):
  Sn = Sn' * CL * CG * CS Sn' = 0.5*SU
     = 25.48125 ksi.       SU = 151 ksi
                           CL = 1
                           CG = 0.75
                           CS = 0.4
Since SC < Sn fatigue life is infinite.
    Corrosion & Wear Analysis
• Pedal surfaces are painted
• Every frictional surface is lightly greased and
  insulated with a plastic bushing so anodic
  corrosion of the material is irrelevant.
• Rod is in contact with the pedal, which gives way
  to adhesive wear.
• Wear: W= KHFS K=10-3
    = 5.0744*10-8 in.3       H= 452.832*103 psi.
    = 8.3154*10-4 mm.3       F = 91.9134 lb.
                             S = 0.25 in.
Disposal

      • Pedal assembly will
        most likely be
        salvaged at end of
        vehicle’s useful life or
        recycled with the rest
        of the vehicle

				
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posted:6/23/2012
language:English
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