PSI - Issue 49

Federico Fazzini et al. / Procedia Structural Integrity 49 (2023) 59–66 / Structural Integrity Procedia 00 (2023) 000 – 000

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from the 36 compression tests, it was possible to obtain the compressive yield load. The values were then averaged for the minimum repeatability of the tests, and their standard deviations calculated for each of the 12 tested configurations, with the summarised results presented in Table 3. Significant variations in elongation at fracture were observed among the different configurations. Specimens with a raster angle of 0°-90° exhibited considerably lower elongation values. For instance, configuration 112-B displayed the minimum elongation with an average value of 1.68%. However, this effect was somewhat mitigated as the extrusion temperature and deposition speed increased. Conversely, configuration 211-O demonstrated the maximum elongation at fracture of 6.62%, while also exhibiting higher values of UTS and tensile Rp0.2. This behaviour can be attributed to the deposition of all tracks along the load axis, providing greater toughness to the specimen. Moreover, specimens with a raster angle of 0°-90° exhibited higher values of Young's modulus due to the rigidity imparted by the filaments deposited orthogonal to the load axis. Configuration 122-I, for example, achieved a maximum Young's modulus slightly below 170 GPa. On the other hand, increasing the temperature, while keeping other parameters constant, did not yield improvements in the tensile properties of the artifacts. In fact, the properties were higher when the extrusion temperature was lower, specifically at 230°C. Furthermore, the increase in deposition speed substantially enhanced the elongation at fracture, while not significantly impacting other mechanical properties. Even for the compressive yield load, it is evident that the most influential parameter is the infill orientation: configurations with a raster angle of 0° exhibit the highest values of compressive yield strength. It should be noted that, with the same printing parameters employed, the compressive yield stress values are significantly higher than their respective tensile values. Figure 2(a) shows the tensile engineering stress-strain curves of the 3 specimens with 112-B configuration (raster angles 0°-90°). Figure 2(b) displays the tensile engineering stress-strain curves of the 3 specimens with 211-O configuration (raster angle 0°). Figure 2(c) and Figure 2(d) shows the tensile engineering stress strain curves of the 3 specimens with 233-Z configuration (raster angles 0-45-90-135) and the compression engineering stress-strain curves of the 3 specimens with 221-V configuration respectively. a b

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