Dependence on mean stress and stress amplitude of fatigue life of EPDM elastomers

Abstract

This paper describes the dependence on test parameters of the fatigue resistance of EPDM. Fatigue was investigated using dumbbell specimens under load control at 1 Hz until failure. Tests were made in order to create a common Wö hler (S-N) curve while increasing the stress amplitude and also to show the influence of increasing minimum stress at constant stress amplitude on fatigue properties. The results of these tests confirmed the well known amplitude dependence of fatigue life in filled rubbers. An additional significant influence on fatigue life is seen to be the minimum stress applied during each cycle to these materials. Fatigue life is not dependent on strain crystallisation in EPDM as it is for natural rubber. The results of this research give component designers the opportunity to increase the fatigue lives of components made from this material.PRC/1743

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

“…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 concept of using a limiting value of E* was further supported by the research of Jerrams et al [23,24] and Hanley et al [25,26] for EPDM samples, both swollen and unswollen, subjected to equi-biaxial stress cycles.…”

Description of fatigue damage in carbon black filled natural rubber

“…This result was first presented Since the end of the 1990s, number of studies dealing with fatigue of carbon black-filled natural rubber (CB-NR) have been proposed. [2][3][4][5][6][7] Similarly to Ref. [1], fatigue tests performed on CB-NR have revealed an improvement of the fatigue life under non-relaxing uniaxial tension loading conditions; this improvement is classically attributed to strain-induced crystallization (SIC).…”

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.…”

“…The dynamic stored energy during cycling of the three sample sets was also evaluated. Previous analyses of uniaxial test data for EPDM found good correlation between the dynamic stored energy in the specimen versus the cycles at failure and its use as a plausible fatigue life predictor was proposed [51][52]. Stressstrain measurements were made periodically throughout the equi-biaxial dynamic tests.…”