Flexural behaviour of pultruded jute/glass and kenaf/glass hybrid composites monitored using acoustic emission

The flexural (before and after cyclic loading up to 50% of ultimate load) and indentation behaviour of pultruded jute/glass and kenaf/glass hybrid polyester composites has been monitored using acoustic emission, and compared with that of kenaf fiber composites. In all hybrids, natural fiber content was 40 wt.%, while glass fiber one was 25 wt.%. Acoustic emission (AE) has been used for real-time monitoring during flexural and indentation loading: the analysis concentrated on AE resuming during reloading (Felicity ratio) and AE activity at low loads during unloading (crack closure effect). The results show that the introduction of this large amount of reinforcement appears quite effective on jute fiber reinforced laminates, although with a significant effect of fiber architecture, whilst it did not yield comparable results in kenaf fiber laminates. This was attributed to the insufficient fiber impregnation and to the need for improving the control of fiber orientation in the laminate.