Ultrasonic Post‐Treatment on Additively Manufactured Short and Continuous Carbon Fiber‐Reinforced Polylactic Acid

ABSTRACT To address the challenges of weak interfacial bonding, low surface accuracy, and insufficient crystallization of additively manufactured fiber reinforced composites, this study utilized a controlled variable approach to investigate ultrasonic post‐treatment effects on short carbon fiber‐reinforced polylactic acid (SCF/PLA) and continuous carbon fiber‐reinforced PLA (CCF/PLA) composites. The effects of ultrasonic pressure and treatment duration on material properties were comprehensively analyzed. Results indicate that optimized ultrasonic treatment markedly enhanced surface quality, minimized internal porosity, and improved mechanical properties in both SCF/PLA and CCF/PLA composites, with CCF/PLA exhibiting particularly notable enhancements. Under ultrasonic pressure of 2 kg/cm 2 and a treatment time of 0.6 s, tensile modulus, flexural modulus, and interlaminar shear strength of CCF/PLA composites increased by 43.6%, 50.8%, and 40.1%, respectively, compared to untreated samples. Ultrasonic post‐processing is anticipated to significantly contribute to the automation of reinforcement processes in additive manufacturing, facilitating broader industrial application.