Fusion Bonding Repair of Impact‐Damaged Elium Laminates: Comparison of Hot Pressing and Joule Heating

ABSTRACT This study investigates the repairability of glass fiber‐reinforced Elium (GFRP/Elium) laminates incorporating nickel‐coated carbon veils, focusing on hot pressing and Joule heating as fusion bonding repair techniques. Thermal analysis established a safe processing window, with Elium exhibiting a glass transition near 99°C, the onset of decomposition at ~300°C, and a major degradation peak at ~400°C. Controlled heating below decomposition but above T _g ensured resin mobility while maintaining stability. Impact testing revealed progressive damage with increasing energy, from matrix cracking at 7 J to severe delamination and fiber fracture at 20 J. Thermal imaging confirmed that disrupted heat flow in conductive veils can also be exploited for damage detection. Compression‐after‐impact (CAI) testing demonstrated substantial strength recovery: at 20 J, residual strength increased from ~125 MPa (as‐damaged) to ~176–184 MPa after repair. Differences in compressive strength between 160°C and 200°C repairs were statistically insignificant, yet microscopy confirmed more extensive crack filling and resin redistribution at 200°C. The superior microstructural healing at 200°C may be critical under cyclic loading or environmental aging. Overall, hot pressing provides benchmark global healing, whereas Joule heating enables localized, in situ repair with integrated damage sensing. These results highlight the potential of veil‐reinforced Elium laminates as sustainable, repairable composites for structural applications in aerospace, wind energy, and beyond.