Influence of functionalized multi-walled carbon nanotubes on the mechanical properties and delamination in drilling of CFRP composites

A study was conducted on the influence of adding carboxyl functionalized multi-walled carbon nano tubes (COOH-MWCNTs) as a filler to carbon fibre reinforced plastics (CFRP) on tensile and flexural properties. In addition to it, the effects of COOH-MWCNTs on delamination of drilled holes in CFRP laminates were also examined. Tensile and flexural tests were performed on a universal testing machine according to ASTM standards. The tensile strength and Young’s modulus of MWCNTs modified CFRP nano composites increased by31.4% and 18% respectively compared to neat CFRP while the enhancements in flexural strength and flexural modulus were 43% and 35.2% respectively. Drilling tests were conducted on CFRP laminates fabricated with neat and MWCNTs filled epoxy matrix. The drilling process parameters evaluated were feed rate, spindle speed, drill diameter and point angle of the drill bit. The delamination analysis of CFRP laminate was performed using digital image processing and adjusted delamination factor was used as a measure of delamination. Using response surface methodology (RSM), the effects of cutting parameters on delamination were analysed. The delamination was observed to decrease with an increase in spindle speed while an increase in feed rate, point angle and drill diameter led to an increase in delamination. The addition of nanotubes to the CFRP composite resulted in an average reduction of adjusted delamination factor by 25.74%.