The Determination of Multi-Axial Fatigue in Magnetorheological Elastomers Using Bubble Inflation

Abstract

Fatigue life is one of the most important physical characteristic that is investigated by materials engineers and scientists. The high dynamic loading experienced by machine parts necessitates understanding fatigue properties in critical components. Despite this requirement, elastomer fatigue criteria are imperfectly understood and even less is known about fatigue resistance in the emerging range of smart elastomers. In this paper, initial research into the equi-biaxial fatigue behaviour of magnetorheological elastomers (MREs) is described. Physical testing was carried out using a bubble inflation testing system. Silicone rubber based test samples were fatigued at different stress amplitudes ranging between 0.75MPa and 1.4MPa using engineering stress as the control mode. S-N (Wöhler) curves showing the plots of stress amplitude (σa) versus cycles to failure (N) are presented. Stress-strain behaviour throughout fatigue process is also described. For a fatigue test at a stress amplitude of 0.75MPa and no pre-stressing, it was found that stress softening occurred for the entire duration of the test, but was particularly pronounced in the first 100 cycles of testing.