Fused deposition modeling of fiber-reinforced thermoplastic polymers: Past progress and future needs

Fused Deposition Modeling (FDM) is one of the most common Additive Manufacturing (AM) techniques for polymeric materials. To improve mechanical properties of the printed parts and improve their dimensional stability, often fibers are added as a reinforcement. This paper provides a thorough review of past work on the FDM process with fiberreinforced polymers. Mechanical properties published in the previous work are summarized. Here, it is differentiated between data of discontinuous fiber-reinforced materials both parallel to the bead direction and transverse to it. Furthermore, available data parallel to the print direction for continuous fiber-reinforced material systems are shown. Next, past modeling work of the FDM method and its related physical phenomena are reviewed and discussed, yet with a special emphasis on FDM with fiber-reinforced polymers. However, due to a lack of published work, promising studies modeling neat polymer behavior are reviewed as well as they can act as initial points for future work. The findings are structured and reported based on these four different research areas of FDM: Material flow and fiber orientation, interface formation, thermomechanical analysis of the deposited material and mechanical characterization of printed parts. Finally, this paper provides a detailed review of the FDM method with fiberreinforced materials and it explains relevant physical phenomena involved in the process as well as their couplings. Based on the review, the current status of the research is evaluated, future needs are formulated and suggestions for ongoing research are given.