Page 30 - MSAM-4-1

Materials Science in Additive Manufacturing TPMS for perfect sound absorption

numerical results demonstrate a shift of the perfect 2 x 2 y 2 y
absorption peak to lower frequencies or a widening of the cos s cos s cos s
perfect absorption frequency range for graded materials. F Iwp 10 *
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The Johnson-Champoux-Allard-Lafarge model was applied cos 2 z cos 2 z cos 2 x

to calculate the sound absorption of a graded primitive (GP) s s s (Ⅲ)
absorber, indicating that the graded direction can affect the 4 4y 4z
x
sound absorption curves. These studies have demonstrated * 5 cos cos cos

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that the graded design can broaden the bandwidth of TPMS s s s
and lower the resonance peak frequency.
In this study, the sound absorption characteristics     π ×sin    π  2y  ×sin sin   π 2x  2z   
of four TPMS structures, including gyroid, primitive,    s    s  s 
I-Wrapped Package (IWP), and diamond, were studied   π  π  2y  π 2x  2z 
using an impedance tube, and laser powder bed fusion +     s ×      ×cos cos    s   s  sin 
(LPBF) technology was applied to manufacture the TPMS F Diamond =10*  π π  2y π 2x  (Ⅳ)
structures. The sound absorption curves and Bloch wave  +   ×cos     ×sin cos    2z  
vector k of TPMS structures are applied to analyze the    s    s  s 
impact of thickness and graded direction on the acoustic  +  π ×cos  π  2y ×cos sin  π 2x  2z  
bandgap and bandwidth. A design method of multicavity      s        s   s  
TPMS is proposed to achieve broadband and perfect sound  
absorption. In addition, a composite design of multicavity and − 0.5*    π + cos    π  8y  + cos cos   π 8x  8z  
graded TPMS structures is further proposed to enhance the   s    s  s 
sound absorption characteristics of acoustic metamaterials.
2.1.2. Design of multicavity TPMS structures
2. Methods
The multicavity structures with four cavity depths were
2.1. Design method designed according to the characteristic that the resonant
2.1.1. Design of uniform TPMS structures frequency of the structure shifts and broadband sound

TPMS cellular structures, including gyroid, primitive, IWP, absorption can be achieved when the cavity depth changes.
and diamond, were generated using MATLAB codes and The design parameters of the multicavity structure are
functions (Equations I-IV). Design parameters are listed listed in Table 2, and the design models are displayed in
in Table 1. The unit cell size was set by parameter s in the Figure 2. For example, the multicavity-gyroid structures
function, and the unit cell size of the uniform structure was were composed of four depth cavities, and each cavity was
set as 3 × 3 × 3 mm. The diameter of the design space was filled with a uniform gyroid structure with 75% porosity,
29 mm, and the structures’ thickness was changed from including Gyroid-12 mm, Gyroid-18 mm, Gyroid-24 mm,
6 to 30 mm. The offset thickness of the surfaces of gyroid, and Gyroid-30 mm. The porosity of all multicavity TPMS
primitive, IWP, and diamond was designed at 0.265, 0.3, structures is 75%.
0.22, and 0.208 mm, respectively, and the porosity of the 2.1.3. Design of graded TPMS
four TPMS structures was fixed at 75%. Design models of
the uniform TPMS structures are displayed in Figure 1. To explore the influence of the graded structure on the
sound absorption characteristics, GP structures were
2 x 2 y 2 y 2 z
F Gyroid sin cos sin cos designed (Figure 3); the designed parameters are listed
s s s s in Table 3. A linear function determined the graded
2z 2x structures of GP. In type I, the unit cell size on the incident
sin cos (Ⅰ)
s s face is 2 mm, and the unit cell size on the rigid face is
4 mm. On the contrary, in type II, the unit cell size on the
2 x 2 y 2 z incident face is 4 mm, and the unit cell size on the rigid
F Prmitive 10 * cos cos cos face is 2 mm.

s s s
2 x 2 y 2 y Multicavity GP type I (multicavity-GP-Ⅰ) structures
cos cos cos were designed with four GP thicknesses, including
5* s s s (Ⅱ) GP-12 mm-Ⅰ, GP-18 mm-Ⅰ, GP-24 mm-Ⅰ, and
2 z 2 z 2 x
cos cos cos GP-30 mm-Ⅰ. Multicavity GP type II (multicavity-GP-Ⅱ)
s s s structures were also designed with four GP thicknesses,

Volume 4 Issue 1 (2025) 3 doi: 10.36922/msam.5737