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Materials Science in Additive Manufacturing TPMS for perfect sound absorption

A B

C D

Figure 19. The upper and lower limits of sound absorption coefficient frequency band above 0.5: (A) uniform triply periodic minimal surface (TPMS) and
multicavity-TPMS, and (B) graded TPMS and multicavity-graded TPMS. The semi-absorption bandwidth of: (C) Uniform TPMS and multicavity-TPMS,
and (D) graded TPMS and multicavity-graded TPMS

multicavity-primitive structures, the multicavity design of further reduce the lower frequency limit. Additionally, the
types Ⅰ and Ⅱ enhanced the noise reduction coefficient by upper limit of multicavity-gyroid, multicavity-primitive,
2.1% and 24.6%, respectively. multicavity-IWP, and multicavity-diamond structures
The upper and lower limits of the frequency band of the are all higher than 6300 Hz, which is the test limit of the
sound absorption coefficient above 0.5 (semi-absorption) impedance tube (500 – 6300 Hz) used in this study.
are displayed in Figure 19A. The diamond structure has The upper and lower limits of the frequency band of the
the lowest frequency lower limit, while the primitive semi-absorption of graded TPMS structures are displayed
structure has the highest frequency lower limit. As the in Figure 19B. As the thickness of GP increases, the lower
thickness of TPMS increases, the lower limit frequency limit frequency of GP-Ⅰ and GP-Ⅱ shifts to a lower frequency.
shifts to a lower frequency. The lowest frequency lower The lower limit frequency of GP-30 mm-Ⅰ is 1250 Hz, which
limit of Diamond-30 mm is 1310 Hz, which is 510 Hz is 570 Hz lower than that of Primitive-30 mm. However,
lower than Primitive-30 mm. The upper limit of the the lower limit frequency of GP-30 mm-Ⅱ is 2160 Hz,
primitive and gyroid structures exhibits a decreasing trend which is 340 Hz higher than that of Primitive-30 mm. This
with increasing thickness, but the upper limit of IWP and highlights that the graded design with a small unit cell size
diamond structures decreases first and then increases on the side of the incident sound wave can lower the limit
with increasing thickness. For the multicavity design of of the semi-absorption frequency, but the graded design
TPMS structures, the multicavity-IWP structure has the with a large unit cell size on the side of the incident sound
lowest frequency (820 Hz), which is 490 Hz and 600 Hz wave increases the lower limit of the semi-absorption
lower than that of Diamond-30 mm and IWP-30 mm, frequency. After the multicavity composite design of GP
respectively. This indicates that the multicavity design can structures, the lower limit of the semi-absorption frequency

Volume 4 Issue 1 (2025) 18 doi: 10.36922/msam.5737