Tension-after-impact (TAI) performance and 3D damage visualization of carbon-fiber epoxy composites with adhesively bonded patch repairs

Bonded repairs are advantageous for the aircraft industry when applying repairs to composite parts. However, their post-impact behavior under mechanical loads has to be addressed. Within this study, CFRP specimens repaired via a soft-patch repair approach as well as pristine (i.e. virgin) laminates without repairs, were impacted (energy: 5 J to 30 J). Subsequently, tensile tests were performed in order to investigate their post-impact mechanical properties. For selected impact energy levels, a detailed analysis on the extent of damage was conducted by micro-CT imaging. From these investigations, the interrelation of the impact energy, the mechanical properties obtained from the post-impact tensile tests as well as of the extent (quantitative and qualitative) and nature of damage could be studied and visualized in 2D and 3D images. Furthermore, a high-resolution image acquired on an undamaged repair-specimen was segmented, from which the individual bond constituents could be identified and visualized in 3D representations.