Effect of nanoalumina on fatigue characteristics of fiber metal laminates

The fatigue life enhancement of fiber metal laminates (FMLs) through embedment of nanofiller into the epoxy has not reported hitherto, and it is the subject of this investigation. Due to its outstanding mechanical properties, nanoalumina is chosen as filler to enhance the fatigue life of FMLs. Tension-tension low cycle fatigue tests were conducted at various stress levels with different percentage of nanofillers, at constant frequency and stress ratio. The results showed that the fatigue characteristics of nano-modified FMLs outclassed the neat epoxy FMLs, and the 0.1-wt percentage of nanoalumina is found to be optimum. Improvement in fatigue life of FML is around 46%, 45% and 94% at a stress level of 50%, 60% and 70% of ultimate tensile strength (UTS) respectively at optimum nanoalumina. The great enhancement in fatigue life is attributed to the combined effect of interfacial strengthening, crack bridging, and pullout of nanoalumina, as evident from macro-to nano-scale fractography.