ARE PSEUDO-DUCTILE ALL-CARBON HYBRID LAMINATES NOTCH INSENSITIVE IN OPEN HOLE TENSION?

The open hole tension response of multidirectional hybrid CFRP laminates with pseudo-ductile (PD) behaviour was investigated by using low- and high-elongation unidirectional (LE/HE UD) CFRP prepregs with conventional thickness. Two stacking sequences [0/45/90/-45]s (QI45) and [0/60/-60]s (QI60) were produced by the sub-laminate [HE/LE/HE] to achieve quasi-isotropy. PD sub-laminates were designed by combining Mitsubishi DIALEAD/ER450 (LE) and Toray T800/ER450 (HE) prepregs. The evolution of damage in the open hole laminates was monitored by digital image correlation (DIC) and acoustic emission (AE) recordings. For the considered laminates, with and without open hole, the pseudo-ductile plateau was clearly detected at almost the same stress level. Moreover, open hole QI60 laminates are notch-insensitive, and QI45 showed a limited notch sensitivity. These results can be helpful for the design of all-carbon hybrid composite components adopting small safety factors.