Co-curing bonding of carbon fibre/epoxy composite joints with excellent structure integrity using carbon fibre/PEEK tapes

A novel co-curing process was proposed for the bonding of carbon fibre/epoxy composites by replacing traditional epoxy adhesives with carbon fibre/PEEK (CF/PEEK) tapes, with an attempt to improve the structure integrity. The lap-shear strengths, fatigue resistance and mode-I and mode-II fracture behaviour of the co-cured joints at 22 degrees C and 130 degrees C were investigated, and the failure mechanisms were also studied. The experimental results demonstrated that, by replacing an aerospace structural adhesive with surface-treated CF/PEEK tapes for the co-curing bonding of composite joints, the lap-shear strength of the joints had been increased by 47% and 68% at 22 degrees C and 130 degrees C, respectively; the fatigue life had been extended by 3.39 times; the mode-I fracture energy had been increased by 70% and 182% at 22 degrees C and 130 degrees C, respectively; and the mode-II fracture energy had been increased by 59% and 54% at 22 degrees C and 130 degrees C, respectively. An analysis on the failure surfaces of the tested specimens proved significant plastic deformation and breakage of the PEEK resin and extensive carbon fibre delamination being the main failure mechanisms of the CF/PEEK bonded joints. Overall, this study demonstrated a huge potential of replacing traditional film adhesives with CF/PEEK tapes for the co-curing bonding of aerospace composite joints with significantly enhanced structure integrity and thermal stability.

Automated summary

A novel co-curing process using carbon fibre/PEEK tapes was proposed for bonding carbon fibre/epoxy composites, resulting in significantly improved structure integrity and thermal stability. The co-cured joints exhibited increased lap-shear strengths, extended fatigue life, and enhanced mode-I and mode-II fracture energies compared to joints bonded with traditional aerospace structural adhesives. The failure analysis revealed that plastic deformation, resin breakage, and carbon fibre delamination were the main failure mechanisms of the CF/PEEK bonded joints.