W. V. Mars

A literature survey on fatigue analysis approaches for rubber

Rubber components subjected to fluctuating loads often fail due to the nucleation and growth of defects or cracks. The prevention of such failures depends upon an understanding of the mechanics underlying the failure process. This paper reviews analysis approaches that are currently available for predicting fatigue life in rubber. Both crack nucleation and crack growth approaches are considered. A discussion of each approachs strengths and limitations, and examples of how these approaches have been applied in engineering analysis are presented.

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

Abstract Many factors are known to influence the mechanical fatigue life of rubber components. Four major categories of factors are reviewed here: the effects of mechanical loading history, environmental effects, effects of rubber formulation, and effects due to dissipative aspects of the constitutive response of rubber. For each category, primary factors are described, and existing literature is presented and reviewed. Rubbers fatigue behavior is extremely sensitive to both the maximum and minimum cyclic load limits. Other aspects of the mechanical load history are also discussed, including the effects of static loaded periods (“annealing”), load sequence, multiaxiality, frequency, and loading waveform. Environmental factors can affect both the short and long term fatigue behavior of rubber. The effects of temperature, oxygen, ozone, and static electrical charges are reviewed. A great range of behavior is available by proper manipulation of formulation and processing variables. Effects of elastomer type...

Observations of the Constitutive Response and Characterization of Filled Natural Rubber Under Monotonic and Cyclic Multiaxial Stress States

This work explores the monotonic and cyclic behaviors of filled, natural rubber. Results of stress-strain experiments conducted under stress states of simple, planar, and equibiaxial tension are presented. The ability of hyperelastic models to capture the observed response, as well as recent developments in constitutive modeling of filled rubber such as the consequences of the Mullins effect, are discussed. Monotonic and cyclic multiaxial experiments were also conducted using a short, thin-walled, cylindrical specimen subjected to a wide range of combined axial and twist displacements. Experiments included pure axial tension, pure torsion, combined loading in which the axial and torsion displacements varied proportionally, and combined loading in which the axial and torsion displacements varied non-proportionally (phase between axial and torsion channels of f50 deg, 90 deg, 180 deg). Results from these tests are presented and discussed, including evolution of stress-strain behavior with load cycles, and the effects of a short period of initial overloading on the subsequent evolution of the stress-strain response. @DOI: 10.1115/1.1631432#

A phenomenological model for the effect of R ratio on fatigue of strain crystallizing rubbers

Abstract The fatigue crack growth rate in strain crystallizing rubbers depends not only on the maximum energy release rate experienced during a loading cycle, but also on the minimum, or equivalently, the R ratio. The R ratio is the quotient of the minimum and maximum energy release rates occurring during a loading cycle. This article proposes a simple phenomenological model for the effect of R ratio on fatigue crack growth rate in strain crystallizing rubbers. The model may also be applied for Wohler-style (S-N style) fatigue life curves. The model is compared against experimental results reported by Lindley, by Cadwell, Merrill, Sloman, and Yost, and by the authors. The ability of the model to represent the experimental data is found to be reasonable. The model provides a simple approach to estimating fatigue performance when limited data are available, and may find application in the analysis of load histories from actual service. Such variable amplitude load histories typically contain cycles covering...

The Effect of a Dwell Period on Fatigue Crack Growth Rates in Filled SBR and NR

Abstract Loading conditions for rubber components are often more complex than the constant amplitude signals used in material characterization. During a series of uniaxial fatigue crack growth expe...

The correlation of fatigue crack growth rates in rubber subjected to multiaxial loading using continuum mechanical parameters

Abstract Although both the crack nucleation and growth stages of the fatigue failure process in rubber are manifestations of the same characteristic material behavior, the nucleation stage deserves...

Constitutive Behavior and Temperature Effects in NR and SBR Under Variable Amplitude and Multiaxial Loading Conditions

Knowledge of the stress response of a material to the applied deformations is necessary for many engineering analysis and applications. This paper addresses the observed effects of load sequencing, Mullins effect, and multiaxial loading on the constitutive behavior of rubber under variable amplitude conditions for a series of experiments using multiaxial ring test specimens. Two filled rubber materials were used and compared in this study; natural rubber, which strain crystallizes, and styrene butadiene rubber (SBR), which does not. A pseudoelastic approach is used to model the cyclic stress-strain response for both materials. The implications of inelasticity when using hyperelastic material models are also discussed. Based on temperature results for the multiaxial ring specimen obtained via a thermal imaging system for SBR, a model capable of accurately predicting surface temperature for the multiaxial ring specimen as a function of hysteresis area and test frequency has been developed.