Page 386 - IJB-10-1

International Journal of Bioprinting Design of dual-unit porous scaffold

Figure 9. The macro-morphologies of the scaffolds after compression test.

exhibit relatively higher compressive strength and lower difference in compressive strength between D and G
elastic modulus. structures was small. At 5% strain, the stress–strain

Figure 9 shows the macro-morphologies of the porous curve of the finite element simulation is similar to that
scaffolds after compression test. The obvious fracture trace of the compression test, showing the same regularity. The
of the scaffold after compression is shown in the red dashed simulated compressive strength is 10–20% higher than the
boxes. In Figure 9A, the angle between the fracture surface compression test result, because the material properties
of G and D structures and the loading direction is 45° (the set under the simulated conditions are ideal conditions,
red dashed boxes), because the scaffold is subjected to shear and the TC4 porous scaffold sample prepared by SLM
stress during compression, 40,47 and the fracture surface of P technology has certain defects in terms of density and
structure is perpendicular to the loading direction (the red surface quality, which inevitably affect the overall strength
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dashed boxes). As shown in Figure 9B, only G-D and D-G of the scaffold.
scaffolds have no obvious densification phenomenon, and the Figure 11 shows the stress distribution of the scaffolds
angle between the fracture surface of G-D and D-G scaffolds after compression simulation. Figure 11A shows the
and the loading direction is also 45° (the red dashed boxes). stress distribution of the three basic structures (P, G, and
The densification of P-G, G-P, P-D, and D-P scaffolds may be D). The main stress concentration distribution area of the
due to the great difference in mechanical properties among P structure is 90° from the direction of the loading force
the P, D, and G structures, and the differences in compressive (the black dashed line), which justifies the failure of the
resistance of the inner and outer layers of the scaffolds can top surface of the P structure in the previous compression
result in densification during the compression. Figure 8B experiment. The stress concentration area of D and G
displays the stress–strain curve, depicting the behavior of scaffolds was about 45° to the Z axis (the black dashed
P-G, G-P, P-D, and D-P scaffolds during compression when line), and the fracture of the D and G scaffolds, as shown
the stress reached the compressive strength of the scaffold. in Figure 9A, was also 45°, because the materials between
At this stage, the local support in the scaffold broke first, the scaffold elements will gradually be compacted and
causing a rapid drop in stress and marking the onset of the eventually fracture along the maximum stress surface.
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yield stage in the stress–strain relationship. Despite this, the Figure 11B depicts the stress distribution cloud map of
scaffold did not experience complete fracture but underwent the scaffolds generated by compression simulation of
gradual compaction.
the scaffold with combined unit. Among them, the P-G
3.3. Finite element analysis of deformation behavior scaffold has the smallest maximum stress concentration
of the scaffolds value (1775.5 MPa), which could explain why the P-G
Figure 10A–E shows the output stress–strain curves of scaffold has the best compressive strength. The G-P
the scaffolds under 5% strain. The order of compressive scaffold has the largest stress concentration value (3539.8
strength of P, G, and D structures was P>D>G; the MPa), but it shows better compression strength due to

Volume 10 Issue 1 (2024) 378 https://doi.org/10.36922/ijb.1263