Study on Ultrasonic Welding‐Scarf Repair Method for Blind Hole Damage on CF/PA66 Thin‐Walled Laminates

ABSTRACT Carbon fiber reinforced thermoplastic composites (CFRTP) are prone to hole‐type damage in commercial aircraft service. This paper proposes a novel repair method that integrates ultrasonic welding with scarf‐repair structures, effectively addressing the limitations of traditional mechanical fastening and adhesive bonding, including inadequate repair performance and prolonged repair cycles, and achieving the efficient restoration of damaged CFRTP components. A dynamic anisotropic viscoelastic model was developed based on the Boltzmann principle. Incorporating the heat generation mechanism of ultrasonic welding, the temperature distribution at the welding interface was analyzed via finite element simulation. The simulation was validated by morphological experiments, and the proposed repair method's effectiveness in restoring tensile strength was assessed. The simulation results align well with the weld morphology, both showing that as excavation depth increases, heat generation decreases, with higher rates at the step edges. Increasing welding amplitude (0–60 μm) and pressure (0–300 N) enhances interfacial heating but risks damaging the base plate. This method significantly enhances efficiency while achieving a repair rate of 82.17%, thus verifying its feasibility for industrial applications.