Experimental investigation on the mixed mode fracture behaviour of nano modified glass epoxy three phase laminated composite through Modified Arcan Fixture

This paper investigates carbon nano tube's (CNTs) effect in the mixed-mode inter-laminar fracture response of glass fibre reinforced epoxy laminates. Laminates are prepared by adding 1%, 2% and 3% of CNTs with matrix by weight. Modified arcan fixture has been employed to generate the data for Mode I, Mode II, and various mixed-mode ratios. Loading angle has varied from 00 to 900 in steps of 150, and the generated data was reduced by applying correcting factors to get toughness value. Periodic function model was employed to estimate the elastic constants for data reduction. Loading angle, Proportion of Carbon Nano Tube, Crack length ratio, Stress intensity factor and Energy release rate are taken as the variables for discussion. Fractured surfaces are also captured with scanning electron microscopy to study the influence of Carbon Nano Tube in inter-laminar fracture. Genuineness of specimen and fixture on exhibiting mixed mode fracture load at crack tip, was verified before proceeding the characterization. Fracture resistance was enhanced from 2.95% to 5.24% and critical load at fracture was increased from 17.47% to 22.79% with Carbon Nano Tube addition compared to the neat GFRP specimens. Enhancement is high for 1% addition, and enhancement rate decreases after further reserves. Failure assessment study was also conducted on specimens and elliptical failure criteria was noted as the best one for defining mixed mode fracture of CNT filled glass epoxy specimens.