A study on the flexural response of grid composites containing multi-walled carbon nanotubes

Grid composite structures (GCSs) owing to their unique shape which is a network of ribs, have some interesting properties such as low strength to weight ratio, low stiffness to weight ratio, high energy absorption capability and good corrosion resistance. In this study, the effect of the multi-walled carbon nanotubes (MWCNTs) addition at various weight percentages with respect to the matrix (0, 0.1, 0.25 and 0.4) on the flexural behavior of GCSs was experimentally examined. For fabricating of the composites, hand lay-up method was used, where plain E-glass and unidirectional carbon fibers impregnated to the resin mixture were used in the skin and rib parts. Afterwards, 3-point bending test was performed on these specimens and the parameters such as maximum flexural load, flexural stiffness and energy absorption were studied. Experimental results showed that, the best flexural behavior was obtained with the addition of 0.4 wt. % of MWCNTs. In this case, the maximum flexural load, flexural stiffness and energy absorption of the GCSs increased by 24%, 35% and 25%, respectively compared to the specimen without MWCNTs addition. The microstructural investigations of the fracture surfaces using electron microscopy clearly indicated the improvement in the interfacial adhesion between the fibers and epoxy matrix in the case of the nanocomposite specimen. This case plays an important role for improvement in the mechanical properties of the GCSs.