PSI - Issue 39

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Mario Álvarez-Blanco et al. / Procedia Structural Integrity 39 (2022) 379–386 Author name / Structural Integrity Procedia 00 (2021) 000–000

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Fig. 1. Parts of a printed prismatic sample.

In addition, no-shell prismatic specimens (i.e. without external walls) were manufactured to allow the visualisation of the inner pattern during test. Hence, these two designs can be compared to study the influence of the lattice core parameters on fracture behaviour. All the tested prismatic samples are summarized in Table 2 with their nomenclature (xN for no-shell specimens and xS for specimens with shell) and different AM parameters.

Table 2. Tested prismatic specimens and FDM process parameters. Sample Infill core density (%) Outer walls Top/bottom layers

1N 2N 3N 1S 2S 3S

30 50 75 30 50 75

0 0 0 1 1 1

0 0 0 2 2 2

In order to generate a homogeneous cover around the inner pattern and create the mentioned shell, note that the number of top and bottom layers is twice the number of outer walls (see Table 2). The reason is that the printing parameters determine a layer height of 0.4 mm and a wall width of 0.8 mm. Fig. 2 shows the different designs of the prismatic specimens 3D-printed in PLA. In the case of the three samples with shell (1S, 2S and 3S), they share the same outer geometry (see Fig. 2(d)) and their lattice cores correspond to the grid patterns shown in Fig. 2(a), (b) and (c), respectively.

Fig. 2. Prismatic specimens: (a) 1N; (b) 2N; (c) 3N; (d) example of one-shell sample.