PSI - Issue 41

Fabio Distefano et al. / Procedia Structural Integrity 41 (2022) 470–485 Author name / Structural Integrity Procedia 00 (2019) 000–000

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Fig. 5 G7 lattice structure stress-strain curves

Table 9. Results of the compression tests E [MPa] σ MAX [MPa] σ med [MPa] TEA [J]

SEA [J*m 3 /kg]

F MAX [kN] 18.2 13.9 14.6

G7_0.05 G7_0.1 G7_0.2

2127 3261 4192

58.8 21.9 22.2 90.5 54.2 14.9 163.7 133.5 10.7

0.025 0.012 0.006

The elastic modulus is an important parameter for the application in the biomechanical field, because values in the range of the elastic modulus of the bone from 0.5 to 20 GPa promote the osteintegration process (Sidambe, 2014); all the tested configurations meet this requirement. Despite G7_0.05 structure presents the higher value of peak force, both compressive strength and crush strength of the investigated microlattice structures increase while relative density increase according with data present in literature (Maconachie et al., 2019) and with the prediction of the Gibson Ashby model (Ashby, 2006). TEA and SEA both decrease while increasing the relative density. 3.3. Gibson-Ashby model The Gibson-Ashby model was applied for the mechanical characterization of the G7 unit cell. In Table 10 are reported to model parameters obtained during experimental tests. The elastic modulus and the compressive strength of the Ti6Al4V ELI alloy were evaluated by some of the authors in a previous work (Epasto et al., 2019b), while the real relative density was calculated as the ratio between the weight and the volume of the specimens. The curves obtained by the interpolation of the relative modulus and relative strength data plotted against the relative density are shown in Fig. 6; furthermore, the mathematical relationship between mechanical properties and relative density is presented. The results are in accordance with data present in literature obtained for unit cell with similar geometric properties of the G7 unit cell (Maconachie et al., 2019).

Table 10. Relative modulus, relative strength and real relative density G7_0.05 G7_0.1 G7_0.2 E c /E m 0.018 0.028 0.036 σ c /σ m 0.058 0.090 0.163 ρ c /ρ m (real) 0.20 0.27 0.38