PSI - Issue 42

C. Boursier Niutta et al. / Procedia Structural Integrity 42 (2022) 1449–1457 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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(a)

(b)

(c) Fig. 6. Comparison of the experimental and numerical results of the lattice structure with d =1.65 mm, l =6.38 mm and n =4: a) force displacement curves; b) comparison for the intrusion of 7 mm; c) comparison for the intrusion of 14 mm [5]. As shown, the whole structure is involved in the collapse with these geometrical parameters. The plastic strain flow obtained through the FE analysis and depicted by the blue beams shows that yielding is not localized to specific layers but affects the whole specimen. As a consequence, the force-displacement curve does not present the peak-and-valley trends. It is worth noticing that this structure was the densest one and also the most performing one. By involving the whole material in the crushing phenomenon, increased SEA is obtained. In conclusion, the FE model is able to capture both the collapsing modes shown by the lattice structures. Its validation allows the investigation of the sensitivity of the structure to the presence of diameter variations and lack of-fusion portions.

4.2 Influence of defects on the SEA

The influence of the diameter variation with respect to the nominal value on the SEA is reported in Fig. 7a, while Fig. 7b shows the 95% confidence interval variation for the investigated defectivity range.