In Situ Thermal Ablation Repair of Delamination in Carbon Fiber-Reinforced Thermosetting Composites

Abstract

Repairing delamination damage is critical to guarantee the structural safety of carbon fiber-reinforced thermosetting composites. The popular repair approaches, scarf repair and injection repair, can significantly restore the in-plane mechanical performance. However, the out-of-plane properties become worse due to the sacrifice of fiber continuity in these repairing processes, leading to the materials being susceptible under service loads. Here, we propose a novel in situ delamination repair approach of controllable thermal ablation in damage removal, achieving a high repair efficiency without impairing the fiber continuity in carbon fiber/epoxy panels. The epoxy resin in the delaminated region was eliminated under the carbonization temperature in a few minutes, allowing the carbon fiber frame to retain its structural integrity. The healing agent, refilled in the damaged region, was cured by the Joule heating of designed electrodes for 30 min at 80 °C, yielding the whole repair process to be accomplished within one hour. For the delaminated carbon fiber/epoxy panels with thicknesses from 2.5 to 6.8 mm, the in-plane compression-after-impact strength after repair could recover to 90.5% of the pristine one, and still retain 74.9% after three successive repair cycles of the 6.8 mm-thick sample. The simplicity and cost-saving advantages of this repair method offer great potential for practical applications of prolonging the service life of carbon fiber-reinforced thermosetting composites.