Abstract
3D printed neat thermoplastic polymers (TPs) and continuous fiber-reinforced thermoplastic composites (CFRTPCs) by fused filament fabrication (FFF) are becoming attractive materials for numerous applications. However, the structure of these materials exhibits interfaces at different scales, engendering non-optimal mechanical properties. The first part of the review presents a description of these interfaces and highlights the different strategies to improve interfacial bonding. The actual knowledge on the structural aspects of the thermoplastic matrix is also summarized in this contribution with a focus on crystallization and orientation. The research to be tackled to further improve the structural properties of the 3D printed materials is identified. The second part of the review provides an overview of structural health monitoring technologies relying on the use of fiber Bragg grating sensors, strain gauge sensors and self-sensing. After a brief discussion on these three technologies, the needed research to further stimulate the development of FFF is identified. Finally, in the third part of this contribution the technology landscape of FFF processes for CFRTPCs is provided, including the future trends.
Highlights
Continuous fiber-reinforced thermoplastic composites (CFRTPCs) have gained considerable attention in automotive and aeronautics applications due to their attractive strength-to-weight ratio, enabling energy and recyclability to be saved as suitable end-oflife scenario
The mechanical testing showed a 50% increase in tensile strength when applying strain perpendicular to the printed lines This finding was explained by the crosslinking reaction between printed lines, in this previous study, the stability of the irradiated specimens was not studied
The greatest magnitude measured for post-fabrication compressive residual strain in a free-standing state, i.e., when the parts are fully detached from the print bed, was related to the specimens reinforced with carbon fibers oriented at 90◦ with a value equal to 3100.2 microstrains
Summary
Continuous fiber-reinforced thermoplastic composites (CFRTPCs) have gained considerable attention in automotive and aeronautics applications due to their attractive strength-to-weight ratio, enabling energy and recyclability to be saved as suitable end-oflife scenario. CFRTPCs appear very attractive, but the scale-up of this promising technology from the prototyping to the production of finished functional components is not straightforward [4] This may be attributed to the long build time and non-optimal mechanical properties of the Published: 4 March 2021. This result can be explained by the presence of three types of interface in molding [10] This result can be explained by the presence of three types of interface the FFF-printed materials engendering non-optimal mechanical properties [5,10,11,12]. FFF-printed materials’ attractivity and enlarge their application range To this end, numerous functionalities have been developed as sensing, self-healing, magnetic properties; Polymers 2021, 13, 789 and growing domain proves to be quite innovative and active. The future trends of this technology are identified (Figure 2)
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