PSI - Issue 53

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C.T. Duarte et al. / Procedia Structural Integrity 53 (2024) 299–308 Author name / Structural Integrity Procedia 00 (2019) 000–000

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Fig. 4. Tensile test set-up.

3. Results and discussions 3.1 Effect of hybridization on mechanical properties Tensile properties

Fig. 5 presents the representative tensile stress-strain curves for all specimens tested as a function of hybridization architecture while Fig. 6 presents the quantitative test data. It can be observed in Fig. 5 that the overall behaviour of the specimens until failure was brittle due to the inherent brittleness of the PLA core, as expected (see Table 1). From Fig. 6a, a trend of increasing tensile strength can be observed as the number of PLA layers increases. With the exception of the A5P5A5 specimens, which showed no significant variation compared to neat ABS, the multi materials exhibited improvements compared to neat ABS. For instance, the A1P13A1 and A3P9A3 cases showed improvements of approximately 32% and 28%, respectively, in tensile strength compared to the neat ABS. In comparison to neat PLA, a plateau was observed in the A1P13A1 and A3P9A3 configurations, while A5P5A5 showed a difference of approximately 17%. Among the multi-material cases, the A5P5A5 configuration exhibited a variation of approximately 22% compared to the other two. Figure 6b presents the Young's modulus in a column chart format. Similar to the tensile strength, the material stiffness increased as the number of PLA layers in the core increased, as expected. The highest stiffness was observed for the A1P13A1 configuration (3.18 GPa), with a difference of approximately 12% and 35% compared to the A3P9A3 and A5P5A5 configurations, respectively. This is due to the combination of a lower number of ABS layers with a higher number of PLA layers, which has superior properties, as seen in Table 1. In comparison to pure ABS, the A1P13A1 and A3P9A3 specimens showed stiffness improvements of approximately 40% and 25%, respectively, while A5P5A5 showed no significant variation. When compared to pure PLA, the A1P13A1 and A3P9A3 groups did not exhibit significant variations (inferior to 10%), but the A5P5A5 specimens showed a decrease of approximately 30%, owing to the lower stiffness of the ABS material. The failure strain of multi-material samples decreased significantly because of the PLA, used in the core, is more brittle than the ABS, used in the outer layers of the sandwich, and it controls the deformation at failure. The same reduction in PLA deformation when exposed to aqueous environments was observed by (Montalvão, G. R. et al. 2020). It was generally observed that as far as tensile strength and modulus are concerned, the plateau tendency visible in Fig. 6 from the A3P9A3 to the neat PLA, show that it is possible to fabricate a material that presents lower moisture ingress due to the ABS envelope, while maintaining the mechanical properties of the superior but more sensitive do environmental degradation PLA.