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Materials Science in Additive Manufacturing Flexural behavior of bio-inspired sutures

sudden drop, it continues with a plateau until the failure of Flexural strength, bending stiffness, and energy absorbed
the whole structure. by each design are given in Figure 5. As shown in Figure 5A,
the flexural strength is significantly higher in the S1 sample
As S3 exhibits the highest displacement, it implies that
the S3 structure can absorb more energy by deforming than than in S2 and S3. With the increment of the positioning
S1 and S2. Further studies on the effect of the positioning angle, the flexural strength gradually decreases compared
angle of the suture structure on flexural properties are to the original S3 sample. The bending stiffness of each
conducted using the S3 specimen design. The positioning design is calculated using the force-displacement curve
slope. Energy absorption is calculated using the area under
angles are varied by 2°, 5° and 8°. The positioning angles
were varied by 2°, 5°, and 8° as given in Figure 3D-F. the force-displacement curve. The bar charts indicate that
The maximum loads of S3-2°, S3-5°, and S3-8° designs bending stiffness decreases gradually with the increment of
the positioning angle. Compared to S1, the absorbed energy
were decreased, respectively, and all three maximum of S2 and S3 is increased by 20% and 48%, respectively.
load values were lower than the maximum load of the Compared to S3, the energy absorption of S3-2°, S3-5°,
S3 specimen. The total displacement of the S3-2° before and S3-8° is reduced by 4.2%, 1%, and 20%, respectively.
the failure is almost similar to the S3, while S3-5° exhibits Considering the flexural strength, bending stiffness, energy
a larger displacement than S3. When it comes to S3-8°, absorption, and failure pattern, different suture structures
the displacement significantly reduces compared to all the can be employed to achieve the desired performances. For
above-mentioned test specimens. The force-displacement example, the S1 design would perform better than S2 or S3,
curves are given in Figure 4B. These results indicate that where higher flexural strength is required, and S3 would
the position of the suture components with respect to the perform better than S1 or S2 in absorbing higher energy.
applied load is a critical factor, and there is a possibility for
further improvement of S3 by allocating the most suitable 3.2. DIC results
positioning angle.
DIC results of strain fields () for S3, S3-2°, S3-5°, and
In all the cases, failure first occurred at the semi suture S3-8° when the fracture starts to propagate are given in
module located at the bottom end of the suture component, Figure 6A-D, respectively. Strains fields generated in both
indicated by first yellow square in Figure 4C-H. In all parts of the specimens are given in the images. The ROI
S3 samples, the second fracture point occurred in the was selected separately for the interlocked parts in the
middle of the suture module. In contrast, in S1 and S2, same specimen to obtain clear strain filed contour plots.
the second fracture point occurred closer to the first one, Higher strain along y-direction was visible in the weaker
which implies in S3 specimens, stress is distributed evenly semi suture module at the bottom of the test specimen,
among all suture modules. which implies high-stress generation.

A

B

Figure 5. (A) Flexural strength, bending stiffness and energy absorption of S1, S2 and S3. (B) Flexural strength, bending stiffness and energy absorption
of S3-2º, S3-5º and S3-8º.

Volume 1 Issue 2 (2022) 6 https://doi.org/10.18063/msam.v1i2.9