FatigueFactors

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

Overview: 

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

Parameters for Simple Histories: 

Parameters for Simple Histories

Effect of Minimum Strain: 

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

Effects of Max. SERR & R-Ratio: 

Effects of Max. SERR & R-Ratio Lindley, Int. J. Fracture, 9, 449 (1973) Unfilled NR

Effect of Static Period under Strain: 

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

Effect of Load Sequence: 

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

Effect of Waveform: 

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

Effect of Strain Rate: 

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

Multiaxial Loading: 

Multiaxial Loading Undeformed Deformed 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? http://www.umi.com/hp/Products/Dissertations.html - “Multiaxial Fatigue of Rubber”, by W. V. Mars, U. of Toledo, 2001

Effect of Temperature: 

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

Temperature and To?: 

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

Effects of Ozone and Oxygen: 

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

Electrical Charges?: 

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)

Polymer / Filler Effects: 

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

Antidegradants: 

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

Proposed Effect of Hysteresis: 

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

Strain Crystallization: 

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

The Mullins Effect: 

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

Tc and Loss Modulus: 

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

SummaryMechanical Load History: 

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

SummaryEnvironmental Conditions: 

Summary Environmental Conditions Temperature Ozone Oxygen Electrical Charges?

SummaryRubber Formulation: 

Summary Rubber Formulation Polymer Type Filler Type and Loading Antidegradants Vulcanization

SummaryStress-Strain Behavior: 

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

Questions and Discussion: 

Questions and Discussion