Effects of natural date palm tree fibres on mode II fracture energy of E-glass/epoxy plain-woven laminated composites

In this study, the effect of date palm tree fibres (DPTF) on the R-curve of E-glass/epoxy end-notch-flexure samples is investigated. To this aim, various DPTF types (Mesh, Rachis, Petiole, Bunch) were treated by 6 wt% of NaOH alkaline solution and then added to the resin in different weight ratios (1.5 and 5%) with sizes of 0.5–2 mm which used for four plies between the 24 plies of composite laminates. Afterwards, the fracture test was conducted according to ASTM standard. The results evidence that natural DPTFs have remarkable potential in the enhancement of the mechanical properties of the woven composite laminates. Accordingly, the addition of DPTFs causes a significant increase in the maximum bearable load as well as the initiation and steady-state fracture energy of the composite. The maximum improvement was 61% in the initiation of fracture toughness for samples with 5 wt% of Petiole fibres whilst the maximum enhancement in steady-state fracture toughness was 73% by adding 5 wt% Bunch fibres. The damage mechanisms at the delaminated interface were analyzed with macro and microscopic images. The Analyses results prove the significant DPTFs contribution in preventing the unstable crack growth which led to more energy consumption at the delaminated interface.