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Materials Science in Additive Manufacturing Energy absorption of Moore’s thin-walled structures
To quantitatively evaluate the performance of fractal dissipated within the first cycle was the highest among all
thin-walled structures during cyclic compression test, six cycles. It could be inferred that both 2 and 3 order
nd
rd
residual strain and dissipated energy (Equation VI) were structures dissipated more energy under LD2 (Figure 12),
calculated and compared in a bar chart (Figure 12). considering the first cycle and all six cycles. Nevertheless,
Recoverability was evaluated by the residual strain, which the residual strains in LD2 were higher than those in LD1.
measures the permanent deformation of structures after a The dissipated energy and residual strain indicated that
cyclic test. Dissipated energy, the strain energy dissipated structures under load in direction 2 experienced more
in a material during cyclic loading, was calculated using permanent deformation.
stored energy during the loading period and the released Table 2 compares the energy dissipation ratios (η) for
energy during the unloading period. Both properties both structures in two loading directions. The 2 order
nd
were measured after only the first cycle and after all six structure had relatively smaller energy dissipation ratios
cycles, considering the difference in behavior during the than the 3 order structure, while both structures were
rd
first cycle and the remaining cycles. Overall, the energy more efficient in LD1 (lower value of η). The residual
A B
Figure 11. Specific energy absorption comparison among different hierarchies and various relative densities during quasi-static compression test from
(A) loading direction 1 and (B) loading direction 2.
rd: Relative density.
A B
C D
Figure 12. Comparisons for residual strain after (A) the first loading-unloading cycle and (B) all six loading-unloading cycles. Comparisons for dissipated
energy after (C) the first loading-unloading cycle and (D) all six loading-unloading cycles.
LD1: Loading direction 1; LD2: Loading direction 2.
Volume 2 Issue 1 (2023) 11 https://doi.org/10.36922/msam.53
