Evaluation of shear properties of carbon nanotube reinforced functionally graded honeycomb composite materials

In the present study, the shear properties of a functionally graded (FG) honeycomb core (HCC) material without and with CNT reinforcement are investigated. The multi walled carbon nanotubes (MWCNTs) functionalized with carboxylic acid (COOH) were randomly added in an organic solvent to disintegrate and disperse homogenously into the viscous less epoxy resin matrix (LY556) using the ultrasonic liquid processor. The FG-HCC composite test materials were made-up without and with CNT reinforcement using high carbon-high chromium honeycomb die using the vacuum assisted hand-layup method. The dynamic analysis of HCC composite materials reinforced with CNT in the ribbon located along the transverse direction was carried out experimentally to identify the shear modulus along the corrugated (G_xz) and joined (G_yz) direction using the alternative dynamic approach method. The materials were functionally tailored in such a way that CNTs were reinforced in ribbon located in between the two honeycomb patters viz, continuously and alternatively, It was shown that the reinforcement of CNT continuous ribbon in the FG honeycomb core materials would increase the shear modulus considerably without any changes in the mass of the composite structure. The strong bonding and random dispersion of CNTs in the FG-HCC composite enhances the shear properties significantly than that of odd and even ribbon sheets reinforced composite structures. This study gives the guidelines for the designer on improving the shear properties of FG-HCC composite structures through CNT reinforcement in the ribbon reinforced core materials.