PSI - Issue 79

Petru Mihai Margitas et al. / Procedia Structural Integrity 79 (2026) 348–353

352

combination of tensile and bending, Fig. 3.b. The sponge-like structure prevented buckling or local buckling. The fracture occurred at 45 ° through the structure by shear. The average and the range of the maximum loads from experimental tests are shown in Fig. 4.a versus the relative density of the lattice, respectively the specific strength ( σ */ ρ *) versus relative density is presented in Fig. 4.b. a b

10 12 14

6000

Square Triangle Sponge-like

Square

Triangle

Sponge-like

5000

4000

0 2 4 6 8

3000

2000

1000 Fracture load [N]

Specific strength [kN m/kg]

0

0.1

0.2

0.3

0.4

0.1

0.2

0.3

0.4

Relative density [ - ]

Relative density [ - ]

Fig. 4 Experimental results from compression test: (a) maximum load, (b) specific strength

It could be observed that the sponge-like structure has the highest relative density and consequently has the highest maximum load and specific strength. The lowest relative density, maximum compression load and specific strength were obtained for the square structure. The energy efficiency of the lattice structures is calculated as the ration between absorbed energy and structure volume, Fig. 5.a. The energy to volume is represented for maximum load (blue) and total energy (red). It could be easily observed that both have the minimum values for square structure and the maximum ones for sponge-like structure. a b

Fmax Total

4

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Square Triangle Sponge-like

0.573

3

E/V* [J/cm 3 ]

2

0.347

1

0.177

C [MPa/J]

0

0

2

4

6

Square

Triangle

Sponge

Compression strength [MPa]

Fig. 5 Energy efficiency of lattice structures: (a) normalized energy to volume, (b) cushioning coefficient