PSI - Issue 56

Laszlo Racz et al. / Procedia Structural Integrity 56 (2024) 3–10 Author name / Structural Integrity Procedia 00 (2019) 000–000

7

5

c)

d)

e)

f)

Fig. 3. Cross-section of the tensile specimens for infill pattern: a) grid 0°-90° b) grid ±45°, c) fast honeycomb, d) full honeycomb, e) triangular 60° and f) wiggle

It can be observed that presence of voids in the cross-section is reduced for grid ±45°, full honeycomb and wiggle infill patterns in comparison with grid 0-90°, fast honeycomb and triangular 60°, fact that will influence the stress strain curves accuracy of the specimens. The shell of the parts is the same, independent of the selected infill pattern. The numerically calculated cross sectional area is presented in Table 2, with that mention that a full cross section has 40mm 2 . In all the six analyzed infill patterns, the extraction position of the cross section was done in the same place for all specimens.

Table 2. Numerically calculated cross-sectional area of the tensile specimens

Specimen’s infill pattern

Calculated cross-sectional area (mm 2 )

Grid 0°-90°

28.75 33.65 31.75 36.45 29.43 37.15

Grid +45°-45° Fast Honeycomb Full Honeycomb Triangular 60°

Wiggle

The cross-section extracted from the geometric model was reintroduced into the testing machine software and the stress results were recalculated according to the new value. Comparative strain-stress curves for all analyzed infill patterns are depicted in Fig. 4. The experimental curves (denoted EXP) are based on a constant cross-sectional area of 40 mm 2 given by the outside dimensions of the specimens and those denoted FEA consider the real cross sectional area presented in Table 2 for each infill pattern. It can be observed that even for a 100% infill rate, there are significant differences between infill patterns, the calculation based on full cross-section will not deliver a result within an expectable error range for some patterns like grid 0-90°, fast honeycomb and triangular 60°, the differences in terms of ultimate tensile strength being 28.1%, 20,6% and 26.4% respectively.