Tension and Compression Properties of 3D-Printed Composites: Print Orientation and Strain Rate Effects

Abstract

This study examines the impact of three factors on the tensile and compressive behaviour of 3D-printed parts: (1) the addition of short carbon fibres to the nylon filament used for 3D printing, (2) the infill pattern, and (3) the speed at which the materials are strained during testing. The results show that adding carbon fibres to the nylon filament reduces variability between tests and emphasises the effect of print orientation. When the infill pattern is aligned with the direction of loading, the tensile strength of all samples increases, with the largest increase of 100% observed in the carbon fibre-reinforced samples, compared to a 37% increase in the strength of nylon samples. The carbon fibre-reinforced samples are also highly dependent on strain rate, with a 60% increase in tensile strength observed at a faster testing speed of 300 mm/min (9 min−1) compared to 5 mm/min (15 min−1). Nylon samples show a decrease of approximately 10% in tensile strength at the same increased speed. The compressive strength of the composite samples increases by up to 130% when the print path is parallel to the loading direction. Increases of up to 50% are observed in the compressive modulus of the composite samples at a test speed of 255 mm/min (9 min−1) compared to 1.3 mm/min (0.05 min−1). Similar trends are not seen in pure nylon samples. This study is the first to report on the variation of Poisson’s ratio of short carbon fibre-reinforced 3D-printed parts. The results show increases of up to 34% and 76% in the tensile and compressive Poisson’s ratios, respectively, when printing parameters are altered. The findings from this research will contribute to the design and numerical modelling of 3D-printed composites.

Delamination Strength Comparison of Additively Manufactured Composite Curved Beams Using Continuous Fibers

“…Nylon White is a stronger and stiffer material by comparison with the conventional nylon used for 3D printers. Fisher et al [44] obtained the elastic tension and compression properties of Nylon White at different strain rates by also considering three different infill parameters including the on-edge orientation used in this study. The material properties of the constituents used in this study are shown in Table 2.…”

Glass Fibre-Reinforced Extrusion 3D-Printed Composites: Experimental and Numerical Study of Mechanical Properties

“…One of the most used fibre-reinforced composite filaments in functional 3D printing is the chopped glass or carbon fibre-reinforced nylon filaments due to their mechanical, chemical, and thermal properties [ 14 ]. Research on the effect of the infill of such materials can already be found [ 15 , 16 , 17 , 18 ], mainly due to the fact that the orientation of fibres inside the nylon should contribute to its mechanical properties significantly, and the most investigated mechanical properties are the tensile and compressive strengths of the samples, which is quite strange considering the fact that fibre reinforcement is commonly used to enhance materials’ flexural strength. However, these studies are quite limited in their scope and do not investigate other important parameters, and the choice of other parameters is hardly stated, and often when they are stated, they seem to be chosen randomly or are the factory presets, which should be modified based on a number of factors.…”

Static Behavior of a 3D-Printed Short Carbon Fiber Polyamide: Influence of the Meso-Structure and Water Content

“…However, the authors applied unconventional deposition strategies, based on a deposition of contour beads only, and a second manufacturing step to obtain such specimens. Fisher et al [10] characterized the longitudinal tensile properties of SCFR-PA6 by testing FFF-ed ASTM D638 [11] standard-complaint dog bone specimens in two configurations: flat specimens, where their gauge length consisted of contour beads only (all parallel to the loading direction), and on-edge 0 • UD specimens, which consisted of all contour beads. Nevertheless, both specimens experienced defect-induced premature failure.…”

“…Nevertheless, both specimens experienced defect-induced premature failure. SCFR-PA6 prism-shaped compression specimens were FFF-ed and tested in accordance with the ASTM D695 [12] standard by Fisher et al [10]. To estimate the transversal isotropic material compressive properties, such specimens were printed by contour beads only in the two following orientations: all the beads of a layer being either parallel or perpendicular with the loading direction.…”

“…They reported a Young's modulus of 1.2 GPa and a tensile strength of about 53 MPa at 38% of strain. Fisher et al [10] tensile tested specimens printed with a default infill deposition strategy (±45 • raster orientations) and two contour beads. About 0.75 GPa of tensile modulus, 28 MPa of strength, and 75% of failure strain were reported.…”