Numerical and experimental investigation on mode I fracture behaviour of titanium/CFRP hybrid composites

In this study, the fracture characterisation under Mode I loading of Ti6Al4V alloy/carbon fibre reinforced polymer (CFRP) hybrid composites was investigated through mechanical testing and numerical simulations. Double cantilever beam (DCB) tests were performed to obtain the critical strain energy release rates (GIC) for the joints of Ti6Al4V/carbon fibre/low melt poly(aryl ether ketone) (CF/LM-PAEK) and Ti6Al4V-carbon fibre/poly (ether ketone–ketone) (CF/PEKK) composites. The Mode I interlaminar fracture energy (GIC) of the joints was evaluated using three different methods, including modified beam theory (MBT), compliance calibration (CC) and modified compliance calibration (MCC). The average GIC values of the LM-PAEK specimen obtained by the MBT, the CC and the MCC methods were 22.3%, 16.3% and 21.2% higher than that of the PEKK specimen. It shows that the LM-PAEK specimen had stronger adhesion than the PEKK specimen bonded with the Ti6Al4V sheet. Simulations were performed to investigate the interfacial behaviour of the Ti6Al4V/CFRP composites based on the cohesive zone model (CZM) using the LS-Dyna software. Results show good agreement between the experimental and the FEA results, with average errors of 2.28% for LM-PAEK and 4.36% for PEKK.