PSI - Issue 53

Alessandro Greco et al. / Procedia Structural Integrity 53 (2024) 178–184 Author name / Structural Integrity Procedia 00 (2019) 000–000

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Fig. 2. (a) specimen geometry; (b) printed specimen series.

The printed specimens were tested under tension by using an MTS Insight 30 electromechanical testing machine, equipped with a 30 kN load cell. The tests were carried out in displacement control with a speed of crosshead equal to 1.5 mm/min. Strains were measured through an MTS axial extensometer with gauge length of 25 mm. As abovementioned, some specimens were subjected to an annealing process considering the temperature curve shown in Fig.3, to study the effects of post-treatment on tensile properties. The annealing was performed within the printing chamber of the miniFactory Ultra, by placing the specimens on the printing plate.

Fig. 3. Annealing temperature curve.

3. Results analysis and discussion Fig. 4 shows the stress-strain curves for some of the specimens tested within the presented experimental campaign. Specifically, 2 repetitions were tested for series 1, 3 and 4, whereas 3 repetitions were tested for series 2. It is worth noting that significantly different tensile behaviors were reported as the infill pattern changes. In general, the rectilinear infill performs better than the triangular, as instance showing significantly more ductile behavior whereas the triangular shows quite a brittle behavior. In contrast, the influence of layer height appears to be less influential on tensile behavior (see. Fig. 5). Fig. 5 shows the histograms for a comparison of tensile properties (i.e., Young’s modulus, ultimate tensile stress and elongation at fracture) among the considered series. The bars represent the average of measurements per each series, whereas the horizontal lines highlight the standard deviations, providing a snapshot