In this study, we present a novel approach for the production of continuous fiber-reinforced thermoplastic composites by combining injection molding and additive manufacturing. After exploring the design requirements, we manufactured inserts via continuous fiber-reinforced 3D printing, then we used them as reinforcement for injection-molded samples. Improper fiber placement can cause warpage as the continuous fibers prevent shrinking; however, warpage can be compensated with the insert geometry. The reinforcement resulted in an increase of about 30% in the properties tested.
We compared the accuracy of analytical models for short fiber–reinforced composites prepared by injection molding and fused filament fabrication (FFF). The microstructural features define the strength of the composites, and they are greatly dependent on the processing conditions. We collected data on fiber length, orientation, and porosity via X-ray micro-computed tomography (µ-CT) and determined the critical fiber length experimentally. We used this data as input for the modified rule of mixtures and the modeling framework based on the Halpin–Tsai method, and found that the cumulative error for FFF is more than twice that for injection-molded composites. We also showed that experimentally determined matrix strength for FFF gives a lower strength limit which is applicable for engineering parts. We presented a new approach for the modeling of the tensile strength of neat FFF products, in which the printed structure is divided into contact zones and bulk material zones. The matrix strength calculated this way was found to approximate the experimental results with an error of 5%.
Munkánkban egy új, hibrid eljárást mutatunk be folytonos szálas, fröccsöntött kompozitok előállítására. Szál- erősített betéteket készítettünk 3D-s nyomtatással, majd ezekre polimer mátrixanyagot fröccsöntöttünk. A befröccsöntött polimer ömledék áramlását és a gyártási paraméterek (kiemelten a szerszámhőmérséklet) hatását fröccsöntési szimulációkkal ellenőriztük. Kísérleteinkkel bemutattuk, hogy aszimmetrikus szálelhe- lyezés esetén az erősítőszálak és a polimer zsugorodása közti különbség vetemedést okoz. A vetemedés kom- penzálását követően 30%-os növekményt értünk el a fröccsöntött kompozitok hajlítószilárdsága és modulusa esetén az erősítetlen referenciához képest.
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