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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.

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Presentation on theme: "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."— Presentation transcript:

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 ACS Rubber Division Meeting Savannah, Georgia April 29, 2002 *Speaker,

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 , –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 Cadwell et al, Ind. Eng. Chem., Anal. Ed., 12, 19 (1940) Filled NR

5 Effects of Max. SERR & R-Ratio 1.E-08 1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 1.E-011.E+001.E+01 Maximum Energy Release Rate, kJ/m 2 Crack Growth Rate, mm/cycle R = 0 R = R = R = 0.35 R = 0.47 Sub-Threshold Regime Transition Regime Power-Law Regime Unstable Crack Growth Lindley, Int. J. Fracture, 9, 449 (1973) Unfilled NR

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

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

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

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

10 Multiaxial Loading UndeformedDeformed H δ max δ min 1 2 Cadwell et al, Ind. Eng. Chem., Anal. Ed., 12, 19 (1940) Applied Loads Crack Loading? Crack Closure? Material property dependence on multiaxial loading? - “Multiaxial Fatigue of Rubber”, by W. V. Mars, U. of Toledo, 2001

11 CIIRNatural RubberBR Effect of Temperature Young, RCT, 59, 809 (1986)

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

13 Effects of Ozone and Oxygen Young, RCT, 59, 809 (1986) CIIRNatural Rubber

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

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

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

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

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

22 Summary Environmental Conditions Temperature Ozone Oxygen Electrical Charges?

23 Summary Rubber Formulation Polymer Type Filler Type and Loading Antidegradants Vulcanization

24 Summary Stress-Strain Behavior Strain-Crystallization Mullins Effect Rate-Independent Hysteresis Viscoelasticity

25 Questions and Discussion


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