Ultrasonic welding and separation of additively manufactured short‑carbon-fiber-reinforced PEKK

This study investigates ultrasonic welding and subsequent ultrasonic-assisted separation of additively manufactured short‑carbon-fiber-reinforced PEKK (PEKK-CF) single-lap joints using ring-shaped PEKK-CF energy directors (EDs). Coupon samples and EDs were produced by laser powder bed fusion and welded at 20 ± 0.5 kHz. Digital light microscopy and micro-computed tomography confirmed proper ED melting and formation of the weld interface. Lap-shear tensile testing demonstrated reproducible joint performance, with comparable maximum forces for both adherend failure and weld spot failure modes. Joined specimens were successfully separated at the weld spot using a wedge-shaped ultrasonic cutting sonotrode. In-situ generator data showed short process time, low peak power, and low energy consumption, highlighting the efficiency of ultrasonic-assisted separation. The results demonstrate the feasibility and potential of combining ultrasonic welding and separation for repairable and circular composite assemblies.