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Factors that Affect the Fatigue Life of Rubber: A Literature Survey

Factors that Affect the Fatigue Life of Rubber: A Literature Survey. W. V. Mars* - Cooper Tire & Rubber Co. A. Fatemi - U. of Toledo Paper #6 (the paper can be purchased at www.rubber.org ) ACS Rubber Division Meeting Savannah, Georgia April 29, 2002. *Speaker, wvmars@coopertire.com.

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Factors that Affect the Fatigue Life of Rubber: A Literature Survey

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  1. Factors that Affect the Fatigue Life of Rubber: A Literature Survey W. V. Mars* - Cooper Tire & Rubber Co. A. Fatemi - U. of Toledo Paper #6(the paper can be purchased at www.rubber.org) ACS Rubber Division Meeting Savannah, Georgia April 29, 2002 *Speaker, wvmars@coopertire.com

  2. Overview • Part I - “A Literature Survey on Fatigue Analysis Approaches for Rubber”, W. V. Mars, A. Fatemi, Int. J. Fatigue, Vol. 24, No. 9, pp. 949-961, 2002. • Crack Nucleation Approach (S-N style) • Crack Growth Approach (dc/dn = f(T)) • Today - Important Factors • Mechanical Load History • Environmental Conditions • Rubber Formulation • Stress-Strain Behavior

  3. Parameters for Simple Histories

  4. Effect of Minimum Strain • Filled NR Cadwell et al, Ind. Eng. Chem., Anal. Ed., 12, 19 (1940)

  5. 1.E-02 R = 0 R = 0.035 R = 0.061 1.E-03 R = 0.35 Unstable Crack Growth R = 0.47 1.E-04 Transition Regime Power-Law Regime Crack Growth Rate, mm/cycle 1.E-05 Sub-Threshold Regime 1.E-06 1.E-07 1.E-08 1.E-02 1.E-01 1.E+00 1.E+01 2 Maximum Energy Release Rate, kJ/m Effects of Max. SERR & R-Ratio • Unfilled NR Lindley, Int. J. Fracture, 9, 449 (1973)

  6. Effect of Static Period under Strain Roland, Sobiesky, RCT, 62, 683 (1989) • Polyisoprene

  7. ε ε ε ε Cycles Effect of Load Sequence Sun et al, TSTCA, 28, 196 (2000)

  8. Effect of Waveform (Both compounds based on BIIR) Pulse Sine Compound B Hardy et al, RubberChem ‘99, Paper #2, Antwerp, Belgium, (1999) Compound A

  9. Effect of Strain Rate Young, RCT, 59, 809 (1986) Unfilled CIIR Unfilled NR

  10. Multiaxial Loading Undeformed Deformed • Applied Loads Crack Loading? • Crack Closure? • Material property dependence on multiaxial loading? δ δ min max H 1 2 Cadwell et al, Ind. Eng. Chem., Anal. Ed., 12, 19 (1940) http://www.umi.com/hp/Products/Dissertations.html - “Multiaxial Fatigue of Rubber”, by W. V. Mars, U. of Toledo, 2001

  11. Effect of Temperature CIIR Natural Rubber BR Young, RCT, 59, 809 (1986)

  12. Temperature and To? n monomer units crosslink Crack tip - Undeformed State L Plane of Crack Propagation crosslink Lake & Thomas, Proc. Roy. Soc. Lon., A, 300 , 108 (1967)

  13. Effects of Ozone and Oxygen CIIR Natural Rubber Young, RCT, 59, 809 (1986)

  14. Electrical Charges? • Electro- & tribo- elastic effects cause electric charges to accumulate under cyclic deformation. • Metallic grips grounded, then insulated. • Effect on fatigue resistance. • Grounded condition gives longer fatigue life • Larger filler loading - larger effect Dogadkin et al, RCT, 33, 970 (1960)

  15. dN / da Polymer / Filler Effects Gum Filled with 50 phr N300 carbon black (fine) + Filled with 50 phr N900 carbon black (coarse) Lake & Lindley, Rubber J., 146 (10), 24 (1964)

  16. Antidegradants Air, Gum NR, No AO Vaccum, Gum NR, No AO Air, Gum NR, +AO Lake & Lindley, Rubber J., 146 (10), 24 (1964)

  17. Proposed Effect of Hysteresis Lake & Thomas, Proc. Roy. Soc. Lon., A, 300 , 108 (1967)

  18. Strain Crystallization Choi & Roland, RCT, 70, 202 (1997)

  19. The Mullins Effect strain time • Progressively Increasing Simple Tension, • N = 8 Mars, Ph.D. Dissertation, U. Toledo, (2001)

  20. Tc and Loss Modulus Data points are for various butadiene-styrene and butadiene-acrylonitrile co-polymers Mullins, Trans. IRI, 35, 213 (1959)

  21. SummaryMechanical Load History • Alternating Load and Maximum Load • Minimum Load, Mean Load, R-Ratio • Statically Strained Rest Period • Load Sequence • Multiaxial Loading • Frequency / Waveform

  22. SummaryEnvironmental Conditions • Temperature • Ozone • Oxygen • Electrical Charges?

  23. SummaryRubber Formulation • Polymer Type • Filler Type and Loading • Antidegradants • Vulcanization

  24. SummaryStress-Strain Behavior • Strain-Crystallization • Mullins Effect • Rate-Independent Hysteresis • Viscoelasticity

  25. Questions and Discussion

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