Simulation of energy dissipation mechanisms in evaluating the critical interlaminar strain energy release rate of cross-ply carbon/epoxy laminated composites

Abstract

Delamination has been introduced as the most crucial failure mechanism in laminated composites due to the absence of reinforcement along the thickness. It is necessary to investigate the phenomenon of delamination by researchers carefully to take full advantage of the composites' valuable properties. The purpose of this study is to quantify the effects of energy dissipation mechanisms on the interlaminar crack growth phenomenon in laminated composites that increase the apparent fracture toughness of these composites. The [0]12, [0/90]6 and [05/90/06] lay-ups made with carbon fiber and the epoxy matrix will be investigated with both experimental and analytical approaches. The results show an increase in the fracture toughness value of the cross-ply laminates compared to the unidirectional ones in the experimental section. According to the observations, it can be said that this increase is due to the difference in the energy absorption mechanisms (so-called toughening mechanisms), including zigzag crack propagation and fiber bridging. Using previous studies, a relationship between different parameters involved in crack growth is presented in the analytical section. Finally, using the J-integral method, the amount of energy absorbed by the fiber bridging mechanism is calculated. Also, a method for quantifying the crack zigzag growth mechanism was presented, which is estimated to increase by about 10% in increasing the fracture toughness value. By removing the effects of energy absorption mechanisms from the R-curve extracted from the experiment, it is observed that the toughening behavior of the graph is eliminated to an acceptable level, which may confirm the hypothesis of the materiality of the fracture toughness parameter in laminated composites.