Advanced additive manufacturing : development of a new process for 3D printed continuous fiber composites

The aim of this work is the development of a new process for 3D printed CFC. A modified 3D printer is used to have a full comprehension of the mechanism that operates under the process. Two main parameters have been selected to have a key role in the working principle. The first is the the ratio between the fiber diameter and the diameter of the nozzle; the second is the combination of the velocity of deposition and the power of the polymerization apparatus. A robotic arm is used, in order to higher the freedom of the movements and allows more complex designs. Thanks to this, a series of print head have been produced. The development of the process was principally oriented to an empirical approach, divided in three activities: the pre-processing of the material through the unwinding of reels and impregnation of the fibers, the design of the print head and the generation of movements through the Grasshopper™ software. The behavior of the material during the deposition process has been studied, in order to achieve better control on the process parameters. A low cost test machine has been designed and used, in order to define optimal process parameters, such as velocity of deposition and power of the polymerization apparatus. The result of the custom test has been compared to standard laboratory test, in order to verify the reliability of this solution. The mechanical properties of the composite material produced have been tested by mean of tensile and bending tests. The section morphology of the samples has been analyzed through a graphical analysis. The main result of the section analysis is the fibers volume fraction. This analysis have been compared to a TGA analysis, showing a good estimation of the fiber volume content. The resin system used is a photopolymer, which can be activated by an UV-radiation of 365 or 405 nm. Fiberglass is chosen as reinforcement material, exhibiting the best printability. The mechanical response of the continuous GF - photopolymerizable resin composite demonstrates that the AM process under study produce high mechanical properties workpiece, compared to other AM process.