PSI - Issue 77

Sergio Cicero et al. / Procedia Structural Integrity 77 (2026) 56–63 Sergio Cicero et al./ Structural Integrity Procedia 00 (2026) 000 – 000

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Table 1. Tensile properties. Material

Raster Orient. E (MPa)

σ u (MPa)

e u (%)

0/90

2241 2388 2329 3769 2751 3313 1050 1053 4135 3972 4065 4002 2797 3496 990

51.7 60.8 59.3 52.0 41.1 42.0 19.4 18.5 16.5 51.0 49.0 44.3 37.5 30.5 39.6

2.8 3.1 2.9 1.7 2.6 1.9 2.8 4.5 2.8 1.4 1.5 1.6 1.8 2.0 1.9

ABS

45/-45 30/-60

0/90

PLA

45/-45 30/-60

0/90

ASA

45/-45 30/-60

0/90

PLA-Gr

45/-45 30/-60

0/90

ASA-CF

45/-45 30/-60

Normalizing the apparent toughness curves with respect to the corresponding fracture toughness value allows for a direct comparison of the notch effect for the five materials (see Figure 3). This comparison is also quantified in the L values shown in Table 2. Both Figure 3 and Table 2 reveal that ASA, along with the lowest fracture toughness values, also presents the lowest notch effect, with L values clearly above 1 millimeter, and with fracture strength increases of less than 20% in the three orientations for 2 mm notch radii. At the other extreme is PLA, with the highest fracture toughness values in cracked conditions and the greatest notch effect of the three raster orientations, especially in the case of the 45/-45 orientation, which with an L of 0.15 mm generates increases in fracture resistance of 108% for a notch radius of 2 mm. This increase is limited to 32% in the 30/-60 orientation and to 40% in the 0/90 orientation. ABS, on the other hand, has a very similar notch effect (and L value) in all three orientations, and of the same order of magnitude as that observed in PLA in the 0/90 and 30/-60 orientations. The increase in fracture resistance in this material for notch radii of 2 mm varies between 24% for the 0/90 orientation, and 44% for the 30/-60 orientation. Finally, the notch effect in the two composites is lower than that in the pristine polymer (i.e., higher L values), in the case of PLA-Gr, and may be higher or lower (depending on the raster orientation being considered) than the pristine ASA in the case of ASA CF. ASA-CF material with raster orientation 0/90 presents a particularly low notch effect. In any case, the notch effect in the two composites is always moderate, as it was the case for the different polymers and raster orientations, with the mentioned exception of the PLA material with raster orientation 45/-45. 4. Conclusions This work presents the fracture resistance results for three polymeric and two polymer-matrix composite materials generated by additive manufacturing: ABS, PLA, ASA, PLA-Gr and ASA-CF. All five materials were generated with three different raster orientations (0/90, 45/-45, and 30/-60) and with their corresponding commercial printing conditions. Fracture resistance was quantified both in the cracked condition (fracture toughness) and in the presence of U-shaped notches with tip radii of up to 2 mm (apparent fracture toughness). The notch effect, quantified using Critical Distance Theory (particularly the Line Method), is greater in PLA and much lower in ASA, which (also) has the lowest fracture toughness values across the entire range of defects