Are classical fibre composite models appropriate for material extrusion additive manufacturing? A thorough evaluation of analytical models

Yan, Jiongyi; Demirci, Emrah; Gleadall, Andrew

doi:10.1016/j.addma.2022.103371

Cited by 13 publications

(17 citation statements)

References 46 publications

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“…For PA-CF, the Z:F ratio of UTS increased by 190%, while remarkably high Z:F ratio of MS was achieved, even greater than 1 for W set -0.6 and 0.7 mm (1.15–1.28), indicating that presence of fibres is more important for MS than interlayer grooves in Z specimens. This agreed the previous finding that fibre reinforcement could increase the strength anisotropy but decrease the strain-at-break anisotropy (Yan et al , 2023a). PA-CF had high strength anisotropy due to highly aligned fibres that reinforced PA in the F direction predominantly, but PA-CF can achieve isotropic ductility at higher W set .…”

Section: Resultssupporting

confidence: 93%

“…A Raise3D Pro2 3 D printer (Raise3DV R ) with a hardened steel nozzle (diameter 0.4 mm) was used for additive manufacturing. Single-filament-wide single-wall boxes, verified in previous research (Allum et al, 2020;Moetazedian, et al, 2021b), were 3D printed, as shown in Figure 1 (Yan et al, 2023a). FullControl GCode Designer was used for toolpath design and parametric control to generate manufacturing code (GCode).…”

Section: Additive Manufacturingmentioning

confidence: 99%

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Controlling anisotropy and brittle-to-ductile transitions by varying extrusion width in short fibre reinforced additive manufacturing

Yan,

Demirci,

Gleadall

2023

RPJ

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Purpose Extrusion width, the width of printed filaments, affects multiple critical aspects in mechanical properties in material extrusion additive manufacturing: filament geometry, interlayer load-bearing bonded area and fibre orientation for fibre-reinforced composites. However, this study aims to understand the effects of extrusion width on 3D printed composites, which has never been studied systematically. Design/methodology/approach Four polymers with and without short-fibre reinforcement were 3D printed into single-filament-wide specimens. Tensile properties, mechanical anisotropy and fracture mechanisms were evaluated along the direction of extruded filaments (F) and normal to the interlayer bond (Z). Extrusion width, nozzle temperature and layer height were studied separately via single-variable control. The extrusion width was controlled by adjusting polymer flow in the manufacturing procedure (gcode), where optimisation can be achieved with software/structure design as opposed to hardware. Findings Increasing extrusion width caused a transition from brittle to ductile fracture, and greatly reduced directional anisotropy for strength and ductility. For all short fibre composites, increasing width led to an increase in strain-at-break and decreased strength and stiffness in the F direction. In the Z direction, increasing width led to increased strength and strain-at-break, and stiffness decreased for less ductile materials but increased for more ductile materials. Originality/value The transformable fracture reveals the important role of extrusion width in processing-structure-property correlation. This study reveals a new direction for future research and industrial practice in controlling anisotropy in additive manufacturing. Increasing extrusion width may be the simplest way to reduce anisotropy while improving printing time and quality in additive manufacturing.

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Section: Resultssupporting

confidence: 93%

Section: Additive Manufacturingmentioning

confidence: 99%

Controlling anisotropy and brittle-to-ductile transitions by varying extrusion width in short fibre reinforced additive manufacturing

Yan,

Demirci,

Gleadall

2023

RPJ

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“…The stress-strain curves of all materials in both F-and Z-directions Figure A3 shows the fibre length distribution and fibre orientation distribution for the theoretical models (Yan et al, 2023).…”

Section: Figure A2mentioning

confidence: 99%

“…For θ measurement, samples were sectioned, as described in Yan et al (2021), and θ of elliptical fibre cross-sections (1,370 in total) were measured. The micrographs of the cross-sections and statistics of cos 4 θ n were included in the Appendix (Yan et al , 2023). The φ 1 was calculated to be 0.36.…”

Section: Theoretical Modelsmentioning

confidence: 99%

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Single-filament-wide tensile-testing specimens reveal material-independent fibre-induced anisotropy for fibre-reinforced material extrusion additive manufacturing

Yan

Demirci

Gleadall

2023

RPJ

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Purpose This study/paper aims to develop fundamental understanding of mechanical properties for multiple fibre-reinforced materials by using a single-filament-wide tensile-testing approach. Design/methodology/approach In this study, recently validated single-filament-wide tensile-testing specimens were used for four polymers with and without short-fibre reinforcement. Critically, this specimen construct facilitates filament orientation control, for representative longitudinal and transverse composite directions, and enables measurement of interlayer bonded area, which is impossible with “slicing” software but essential in effective property measurement. Tensile properties were studied along the direction of extruded filaments (F) and normal to the interlayer bond (Z) both experimentally and theoretically via the Kelly–Tyson model, bridging model and Halpin–Tsai model. Findings Even though the four matrix-material properties varied hugely (1,440% difference in ductility), consistent material-independent trends were identified when adding fibres: ductility reduced in both F- and Z-directions; stiffness and strength increased in F but decreased or remained similar in Z; Z:F strength anisotropy and stiffness anisotropy ratios increased. Z:F strain-at-break anisotropy ratio decreased; stiffness and strain-at-break anisotropy were most affected by changes to F properties, whereas strength anisotropy was most affected by changes to Z properties. Originality/value To the best of the authors’ knowledge, this is the first study to assess interlayer bond strength of composite materials based on measured interlayer bond areas, and consistent fibre-induced properties and anisotropy were found. The results demonstrate the critical influence of mesostructure and microstructure for three-dimensional printed composites. The authors encourage future studies to use specimens with a similar level of control to eliminate structural defects (inter-filament voids and non-uniform filament orientation).

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The role of the fiber–matrix interface in the tensile properties of short fiber–reinforced 3D‐printed polylactic acid composites

Tóth,

Lukács,

Kovács

2024

Polymer Composites

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In this study, we investigate the relationship between structure and properties of fiber–matrix adhesion for material extrusion–based 3‐dimensional (3D) printed composites. We examine the influence of fiber length and fiber content on the tensile properties of glass, basalt, and carbon fiber–reinforced polylactic acid (PLA) composites. Short fiber–reinforced filaments were produced, then, simple micromechanical models were used to predict the in‐plane tensile properties. We found that interlayer tensile properties are strongly influenced by fiber–matrix adhesion. If adhesion is sufficient, the fibers and matrix deform together under tensile load. A second‐order relationship describes interlayer tensile strength in relation to fiber content between 5 and 25 w%, with a maximum at 15 w%, for carbon and basalt fiber–reinforced composites. If adhesion is weak, the crack propagates along the fiber–matrix interface, causing brittle fracture and low strength. This behavior was noted for the glass fiber composite, for which the calculated interface shear strength was the lowest (1.4 MPa). In this case, fiber content is inversely proportional to interlayer tensile strength. Our results show the role of fiber–matrix adhesion quality on tensile properties, which has a major impact on both the accuracy of predictions and the damage processes.Highlights Critical fiber length determines accuracy of tensile property estimates Quality of fiber–matrix adhesion governs interlayer damage process Poor adhesion causes brittle fracture and low strength Second‐order relationship of interlayer tensile strength and fiber content Loss of interlayer tensile strength in composite due to fiber–matrix interface

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Are classical fibre composite models appropriate for material extrusion additive manufacturing? A thorough evaluation of analytical models

Cited by 13 publications

References 46 publications

Controlling anisotropy and brittle-to-ductile transitions by varying extrusion width in short fibre reinforced additive manufacturing

Controlling anisotropy and brittle-to-ductile transitions by varying extrusion width in short fibre reinforced additive manufacturing

Single-filament-wide tensile-testing specimens reveal material-independent fibre-induced anisotropy for fibre-reinforced material extrusion additive manufacturing

The role of the fiber–matrix interface in the tensile properties of short fiber–reinforced 3D‐printed polylactic acid composites

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