Abstract

The development of 3D printed composites showing increased stiffness and strength thanks to the use of continuous carbon fibers has offered new prospects for Fused Filament Fabrication (FFF) technique. This work aims to investigate the microstructure and mechanical properties of 3D printed CCF/PA composites with various layups, and also to apply predictive models. The mechanical properties of the printed parts were directly related to the adopted laminate layup as well as to the microstructure and defects induced by the FFF process. The highest stiffness and strength were reported for longitudinal composites, where the fibers are unidirectionally aligned in the loading direction. In addition, it was found that the reduction in tensile properties obtained for cross-ply and quasi-isotropic laminate layups can be described by using the Angle Minus Longitudinal. A step-like failure with extensive fibers breakage and pull-out was observed for the longitudinal composites. By contrast, the rupture mode of the quasi-isotropic laminates mainly exhibited debonding between beads. Moreover, the predictions obtained using the Volume Average Stiffness method and Classical Laminate Theory were in good agreement with the tensile test results. This work could help engineers to design complex laminates with specific mechanical requirements by tailoring the orientation of continuous carbon fibers.

Highlights

  • The results showed that Classical Laminate Theory (CLT) accurately predict the Young’s modulus and Poisson’s ratio for a wide range of laminate layups

  • The shape and the distribution of these voids depend on the adopted laminate layup: the non-homogeneous temperature fields generated during printing of cross-ply and quasi-isotropic samples promote the formation of large voids between layers, while the longitudinal composites exhibit porosities mainly in the inter-bead areas; The mechanical performances are strongly affected by the laminate layup as well

  • It was found that the mechanical properties of laminates gradually decrease as a function of the Angle Minus Longitudinal value

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Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Method to predict the elastic properties of 3D printed CFRPA composites with different fiber content and infill patterns. The method involves a volume averaging of the stiffness matrices of the different regions of the fiber reinforced composites, namely shell, solid and infill Both studies showed a good agreement between the predicted elastic moduli and Poisson’s ratio values and the experimental data [26,35]. Demonstrated the validity of the Classical Laminate Theory (CLT) to model the elastic properties of highly oriented short carbon fiber reinforced composites produced using a common FFF printer. (CLT) to model the elastic properties of highly oriented short carbon fiber reinforced com of 26 posites produced using a common FFF printer.

Methods
Samples Production
Filaments and 3D Printed Samples Characterization
Modeling Approaches
11 Vwalls
Properties
Microstructure and Voids
Tensile Properties and Fracture Surfaces
10. Macroscopic
Comparison of Modeling Results with Experimental Data
VAS Method
Conclusions
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