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Rubbers possess unique mechanical properties that make them indispensable for technological products such as seals and tires, which are normally subjected to quasi-static loading conditions which superimposes cyclic loads; their failure is mainly related to fatigue. In this study the focus is on the effect on fatigue of parameters connected to the mechanical history. Fatigue crack growth of a non-crystallizing rubber was investigated using cyclically loaded pure shear specimens considering different loading conditions. In a first step, the geometry of the specimens, in terms of width to height ratios and notch length, was considered to avoid specimen-influences on the results. Subsequently, several tests were implemented using both force and displacement control with different loading histories. Finally, the effect on the fatigue crack growth of parameters such as waveform, frequency and load ratio was investigated. In general, no significant influence of load or displacement control was found. Among the loading parameters, waveform and load ratio seem not to have a marked effect on the fatigue behavior of the material. In contrast, decreasing values of frequency were found to increase the crack growth rate. |
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