Multifunctional carbon-veil grid design for impact damage monitoring and tolerance in GFRP and CFRP laminates

• A multifunctional laminate with embedded carbon-veil grids enables impact sensing without sacrificing strength. • Layer-resolved resistance pinpoints impact damage, including hidden subsurface regions. • Patterned thermoplastic–carbon-veil interleaves boost interlaminar shear strength while preserving integrity. This study presents a materials-by-design strategy based on fully embedded carbon-veil grid architectures for high-sensitivity impact damage monitoring in glass- and carbon-fibre-reinforced polymer (GFRP and CFRP) laminates. Integrated as part of the laminate, the architecture exploits high-frequency resistance monitoring to capture transient electrical responses during impact, enabling detection of damage initiation at very low energy levels. In GFRP laminates, lightweight 10 g/m 2 carbon-veil grids produced repeatable and spatially resolved resistance responses under low-velocity impacts between 5 and 20 J. Distinct transient resistance signatures were detected even at 5 J, revealing sensitivity to early-stage matrix cracking beyond conventional post-impact measurements. With increasing impact energy, transient and permanent resistance changes increased markedly, reaching very large amplitudes at 20 J due to extensive delamination and grid disruption. In CFRP laminates, electrically insulated 2 g/m 2 carbon-veil grids combined with thermoplastic veils enabled detection of subsurface and through-thickness damage at energies as low as 3 J, even in the absence of visible ultrasonic indications. Joule-heating-assisted thermal imaging provided direct visualisation of electrically damaged regions, while short-beam shear tests showed an approximately 11 % enhancement in interlaminar shear strength. The architecture enables early impact damage detection, severity discrimination, and mechanical enhancement in composite laminates.