PSI - Issue 28

Costanzo Bellini et al. / Procedia Structural Integrity 28 (2020) 667–674 Author name / Structural Integrity Procedia 00 (2019) 000–000

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The produced specimens were tested according to the ASTM D7250, that is suitable for the determination of the flexural properties of sandwich constructions. In fact, the produced panels can be classified as sandwich structures; moreover, the analysed lattice structures are generally loaded with flexural loads in their service life. The test scheme consisted in the typical three-point bending flexure: the specimen was placed on two supports and it was loaded in the centre by a loading nose. In Fig. 4 both types of specimens can be seen during the three-point bending test.

a

b

Fig. 4. Additively manufactured metal lattice structure: a) with metal skin, b) with CFRP skin.

3. Results The data obtained from the experimental test campaign are reported in Fig. 5. In particular, in the graph a single load-displacement curve was plotted for each type of specimen, that was representative of the results relevant to the five specimens tested for each type. The coefficient of variation relevant to each kind of specimen was 8% at maximum, denoting the very high repeatability of the manufacturing process.

Fig. 5. Load-displacement curves for the tested specimens.

From the data reported in Fig. 5 it can be noted that the all-titanium specimen presented a higher strength and a higher strain to failure respect to the hybrid one. In fact, the maximum load supported by the former one was about 3000 N, while the other one reached a lower maximum load, equal to 1200N. As concerns the maximum displacement, also in this case the maximum value reached by the all-titanium specimen was higher than that belonging to the hybrid one: in the former case it was 9.8 mm, while for the other one it was 6 mm. It must be noted that for the hybrid