Abstract
The current study explores the effects of geometrical shapes of the infills on the 3D printed polylactic acid (PLA) plastic on the tensile properties. For this purpose, by utilizing an accessible supply desktop printer, specimens of diamond, rectangular, and hexagonal infill patterns were produced using the fused filament fabrication (FFF) 3D printing technique. Additionally, solid samples were printed for comparison. The printed tensile test specimens were conducted at environmental temperature, Ta of 23 °C and crosshead speed, VC.H of 5 mm/min. Mainly, this study focuses on investigating the percentage infill with respect to the cross-sectional area of the investigated samples. The mechanical properties, i.e., modulus of toughness, ultimate tensile stress, yield stress, and percent elongation, were explored for each sample having a different geometrical infill design. The test outcomes for each pattern were systematically compared. To further validate the experimental results, a computer simulation using finite element analysis was also performed and contrasted with the experimental tensile tests. The experimental results mainly suggested a brittle behavior for solidly infilled specimen, while rectangular, diamond, and hexagonal infill patterns showed ductile-like behavior (fine size and texture of infills). This brittleness may be due to the relatively higher infill density results that led to the high bonding adhesion of the printed layers, and the size and thickness effects of the solid substrate. It made the solidly infilled specimen structure denser and brittle. Among all structures, hexagon geometrical infill showed relative improvement in the mechanical properties (highest ultimate tensile stress and modulus values 1759.4 MPa and 57.74 MPa, respectively) compared with other geometrical infills. Therefore, the geometrical infill effects play an important role in selecting the suitable mechanical property’s values in industrial applications.
Highlights
An engineering design involves a basic idea, proper planning, material selection, and an optimized manufacturing process regardless of the desired product or component.The proper execution of all steps to make an engineering product or component results in significant benefits in terms of low expenditures, decrease in the chances of failures during service, and reduced manufacturing time, which gives significant advantages over other market competitors
In order to increase the accuracy of output data, some of the important parameters of the tensile test are adjusted to ensure the test is aligned with the guidelines dictated in ASTM
Based on the observations mentioned above, it is suggested that the behavior of solidly infilled specimen may be attributed to the relatively high infill density and good bonding adhesion between the printed layers that make the solidly infilled specimen structure stiffer and brittle, while rectangular, diamond, and hexagonal infill patterns showed ductile-like behavior, possibly due to relatively loose bonding between printed layers and fibril connections and structures
Summary
An engineering design involves a basic idea, proper planning, material selection, and an optimized manufacturing process regardless of the desired product or component. The influences of raster angle, raster width, and layer height on the FFF-printed PLA flexural properties were investigated by Rajpurohit et al [19]. Luzanin et al [21] have studied the influence of raster angle, layer height, percentage infill, extrusion temperature, and speed on the flexural behavior of the PLA parts. They reported the highest flexural strength at 0◦ raster angle. The current research aims to observe the infill structure effects on the tensile properties of 3D printed PLA components to provide the designers and industrial manufacturers with an understanding of the FFF of the 3D printing technique. The study presents a comparison between the infill percentages in solid infill configuration by means of 100% infill and other patterns with percentage of 15% infill
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