PSI - Issue 68

Estera Vălean et al. / Procedia Structural Integrity 68 (2025) 955 – 961 Vălean et al./ Structural Integrity Procedia 00 (2025) 000–000

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2.2. Dynamic Results - Impact tests The impact force versus the deflection curves obtained during the impact test are shown in Figure 4a. As in static tests, the maximum impact force is higher for PLA, smooth specimen. As can be seen for all specimens except PLA notch, the maximum force appears at the last peak. In the case of PLA-notch, the maximum force of 140 N appears at the 3rd peak out of 4. As in the static tests, the forces have much higher values large for the smooth samples compared to the notched ones, in the case of the PLA material the difference between the strength values is approximately 68%, and for PLA CF, the notch brings a decrease in strength of 78%.

0 0,1 0,2 0,3 0,4 0,5 0,6

-50 50 150 250 350 450

(b)

(a)

(a)

Impact Force [N]

Impact Energy [J]

0

1

2

3

0 0,5 1 1,5 2 2,5

Deflection [mm]

Deflection [mm]

20

(c)

12,93

10

10,29

1,94

0,72

0

Impact strength [kJ/m²]

PLA PLA-CF PLA-notch PLA-CF-notch

Material and specimen type

Fig. 4. Impact force-deflection (a), impact energy – deflection (b) and impact strength for various with type of sample (c)

The impact energy defined according with ISO 178 (2019), is higher for the unreinforced material both for the notched and for the smooth samples (Figure 4b). The highest value of 12.93 kJ/m² was obtained in the case of smooth PLA, and the lowest value of 0.72 kJ/ m², was obtained in the case of notched PLA-CF specimen (Figure 4c). The impact strength values of 1.94 kJ/m 2 obtained for the notched specimens from PLA are similar to the results obtained by Milovanović et al (2024). They investigated the specimens with two outlines and a honeycomb infill structure. Likewise, different layer thickness values, namely, 0.1 mm, 0.2 mm, and 0.3 mm.