Abstract: Continuous fiber reinforced composites additive manufacturing has the advantages of high forming freedom, high material utilization rate and low die dependency, which can realize the rapid and low-cost integrated manufacturing of composite materials and satisfy the short-cycle and high-performance forming requirements in aerospace and other fields. However, the layer-by-layer stacking form leads to poor interlaminar performance, which easily induces delamination in the long-term service and seriously limits its wide application. In this study, a continuous fiber additive manufacturing forming method based on laser in-situ preheating is proposed. By establishing a finite element simulation model based on the "life and death element" technology, the temperature distribution and evolution on additive manufacturing are revealed, and its effective performance on improving the interlaminar performance of formed parts is verified through experiments. Finally, the interlaminar strengthening mechanism of laser preheating is obtained. The results show that laser preheating can rapidly heat the surface and internal temperature of the sample, promote the bonding of resin between layers and the remelting and impregnation of internal wire materials. Compared with the sample without preheating, the interlaminar shear strength of the preheated sample is increased up to 115%.

Key words: continuous fiber, additive manufacturing, laser preheating, interlaminar strengthening, birth-death element