The rate-dependence of flexural shear fatigue and uniaxial compression of carbon- and aramid-fibre composites and hybrids

The purpose of this work is to provide important insight into the factors that determine the unique flexural-fatigue performance of aramid-fibre/carbon-fibre (ACA) sandwich hybrid composites and its dependence on strain rate. The understanding of the response to strain rate of the single components under compression and shear conditions is the focus of this paper. Axial-compression strength, static-shear, and shear-fatigue results as a function of strain rate are analysed independently and compared in an attempt to explain the flexural behaviour of the ACA hybrid. The possibilities that the rate-dependence of the flexural-fatigue behaviour of the ACA hybrid result from contributions of those components are eliminated. The likely source of this behaviour may be related to the strain-rate gradient for the ACA beam under flexural loading, which follows the plastic yielding in compression of the aramid skin.