The effect of minimum stress and stress amplitude on the fatigue life of non strain crystallising elastomers

Fatigue life prediction of magnetorheological elastomers subjected to dynamic equi-biaxial cyclic loading

“…It can be noted that at a constant stress amplitude, the dynamic stored energy increases with the accumulation of cycles for both isotropic and anisotropic MREs. When plotted against log10 cycles to failure, the dynamic stored energy at failure was found to decrease linearly, indicating that, as suggested by Abraham [19] and others [22,24], dynamic stored energy can be used as a plausible predictor of fatigue lives for isotropic and anisotropic MREs irrespective of the stress amplitudes applied.…”

“…It is usual for the modulus of a filled rubber to decrease significantly in the first few cycles of a physical test as a result of the Mullins effect [19]. Previous research into fatigue of non strain-crystallising elastomers (ethylene propylene diene monomer, EPDM and styrene-butadiene rubber, SBR) by Abraham [20,21] and Alshuth et al [22] suggested that when subjected to uniaxial loading these materials exhibited a limiting value of complex tensile modulus (E*) and this value could be used effectively to design against fatigue failure in rubber components.…”

The Significance of Equi-Biaxial Bubble Inflation in Determining Elastomeric Fatigue Properties

“…As a result, an energy criterion was postulated. Another important effect was highlighted in this research [50,51,52]. As load cycles were accumulated, it was observed that most mechanical properties changed, but in particular the stiffness of specimens changed throughout the full duration of the fatigue tests; an equilibrium material stiffness was never reached.…”

“…Abraham [47] investigated the fatigue life and dynamic crack propagation behaviour of nonstrain crystallising elastomers to determine their dependency on test parameters. The research culminated in recommendations of criteria for precise prediction of service life for components formed from these compounds.…”

“…The system can also be used to determine static failure strength, stress relaxation, creep, stress softening and set for dynamic equi-biaxial loading. As stated, the initial impetus for the research was to determine if Abraham's findings [47] in uniaxial fatigue testing of non-strain crystallising rubbers were confirmed for biaxial loading. Very little research had been carried out previously using dynamic bubble inflation of rubber, though Bhate and Kardos [75] used bubble inflation to study high frequency vibrations in elastomers and Hallett [76] studied equi-biaxial rubber fatigue without integrating the systems essential to allow full control of the tests.…”