Page 51 - eBook_Proceedings of the International Conference on Digital Manufacturing V2

Enhanced Bending Strength of PLA Beams with Varied Lattice Infill Structures

Table 6: Behaviour of beam in three-point testing at constant
porosity of 70% with emphasis on lightweight characteristics in
comparison to solid beams.

Displacement (mm)
Lattice 2 5 10 15 20
Structure
Stress to mass ratio (MPa/g)
BCC 2.49 6.24 12.47 18.71 24.94
FCC 2.74 6.85 13.70 20.55 27.40
Kelvin 2.65 6.62 13.24 19.86 26.49
Octet 2.88 7.16 14.31 21.47 28.63
HX HC 5.32 13.29 26.61 39.92 53.22
TRI HC 2.10 5.26 10.52 15.79 21.05
Fluorite 2.47 6.18 12.37 18.55 24.74
Diamond 2.35 5.87 11.73 17.60 23.47
Gyroid 2.22 5.53 11.06 16.60 22.13

This is achieved by vertically shifting the midpoint of a two-
pillar beam. Using this method, direct comparisons of material
efficiency can be made between different lattice structures as
deformed when under increasing loads (2mm to 20mm). The
larger stress-to-mass ratio generally characterises the more
efficient structure that resists more stress without much
consumption of material. This logic informs us that Hexagonal
Honeycomb (HX HC) is the lattice with the maximum stress-to-
mass ratio and thus emerges to be highly efficient in offering load
capacity per unit weight. HX HC has a greater deformation
(equivalent strain) value compared to others, which is a
compromise because HX HC is more efficient in handling stress,
but at the cost of deforming more. This characteristic brings HX
HC on par with Triangular Honeycomb.

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