PSI - Issue 47

Mohammad Reza Khosravani et al. / Procedia Structural Integrity 47 (2023) 454–459 Author name / Structural Integrity Procedia 00 (2023) 000–000

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fracture toughness decreases at a higher printing speed. The CT test coupons after the fracture tests are illustrated in Fig. 3. Experimental CT tests show that in the case of 0 ◦ / 90 ◦ filament orientation, the crack propagated parallel to the initial crack, but in 45 ◦ / -45 ◦ specimens,he crack growth occurred 45 ◦ to the initial crack. Indeed, the crack growth occurred along the filament deposition direction.

Fig. 3. Fractured specimens with di ff erent filament orientations; 0 ◦ / 90 ◦ (left), and 45 ◦ / -45 ◦ (right).

In CT tests, the load–displacement data were recorded and demonstrated in Fig. 4. The highest fracture load is 7809.24 ± 17 . 1 N belongs to 45 ◦ / -45 ◦ specimen printed at 20 mm / s. In addition, lowest fracture load is 5438.01 ± 7 . 4N obtained from CT test on fabricated 0 ◦ / 90 ◦ PLA specimen printed at 80 mm / s. This experimental investigation con firmed that fracture load decreased while printing speed increased. At the lower print speed (20 mm / s), the filaments are closely packed, and filaments are fused together. This leads to a continuous medium for crack propagation. The strain energy can be estimated by calculating the area under the load–displacement curves.

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Fig. 4. Load-displacement curves of CT specimens; 0 ◦ / 90 ◦ (left) and 45 ◦ / -45 ◦ (right), fabricated with di ff erent printing speeds.

Although there is a rapid growth in applications of 3D printing, some technical limitations and lack of suitable standards methods for evaluation of 3D-printed parts should be considered as barriers in advanced manufacturing via 3D printing. However, some available standards methods like CT test on plastic materials can be used in the field of 3D printing to overcome the hinders in this field.

4. Concluding remarks

Du to the applications of 3D-printed parts as functional end-use products, their mechanical strength has become of significant importance. Therefore, di ff erent tests have been used to determine structural integrity of additively manufactured components. In the current study, we have conducted CT test to investigate the fracture behavior of 3D printed parts. Since printing parameters have e ff ects on the mechanical strength of 3D-printed parts, the specimens were printed with 45 ◦ / -45 ◦ and0 ◦ / 90 ◦ filament orientations at printing speed of 20 mm / s and80mm / s. On the basis of