Reversing Fatigue Damage in Carbon Fiber–Thermoplastic Composites Using Localized Plasma Heating

ABSTRACT Thermoplastic composites offer promising pathways for recyclable and rapidly manufacturable structural materials but suffer from limited repair strategies post‐fatigue damage. We demonstrate that plasma‐based heating can reverse mechanical degradation in short‐fiber carbon fiber/ABS composites fabricated via additive manufacturing‐compression molding (AM‐CM) process. Localized Joule heating in the conductive carbon fibers due to plasma‐composite interactions leads to volumetric matrix softening and enhanced polymer chain mobility, thereby facilitating damage healing. Mechanical testing revealed a 36% increase in yield strength following plasma treatment, recovering 91% of the strength lost to fatigue. Thermogravimetric and thermomechanical analyses established safe processing windows, while optimization of plasma parameters (gas flow: 46 L/min, nozzle rotation speed: 2800 rpm, standoff: 7 mm, speed: 10 mm/s) enabled reproducible repair conditions. Microstructural imaging confirmed matrix void closure due to localized melt flow. This work establishes a scalable, in situ repair approach for extending the service life of thermoplastic composites in load‐bearing applications.