Rate-dependent fatigue of aramid-fibre/carbon-fibre hybrids

A previously observed hybrid effect in the flexural fatigue behaviour of aramid-fibre (A)/carbon-fibre (C) reinforced hybrid is re-examined as far as this effect can be attributed to the loading-rate dependence of the hybrids. This research comprises an investigation of the fatigue behaviour of composites distinguished by its combination of experimental conditions, including the materials, loading mode and rate of loading. Unidirectional carbon-fibre/aramidfibre reinforced hybrids were tested in flexure under a range of strain rates, in order to investigate the hybridization effect on the rate dependent fatigue behaviour. The ACA sandwich hybrid, whose fatigue performance is far better than that of the CAC hybrid, and which exhibits an improvement even with respect to the aramid parent composite, exhibits a clear strain-rate dependence. The different performances of the two hybrids are ascribed to the different rate dependences of the compressive and tensile strength of the parent C and A composites.