Abstract:

Objective: In order to provide theoretical basis for developing of bionic wood sound absorption material, the sound absorption structure of the bionic wood is designed according to the wood structure. Then, the hole angles of the absorption structure are tested. Method: First of all, we modeled the bionic wood sound absorption structure with Rhinoceros 3D software, and prepared this structure by 3D printing technology. The influences of different inclined angles(15°, 30°, 45°, 60°)on the resonant frequency and sound absorption coefficient were investigated by means of impedance tube transfer function. Then, the sound absorption properties of 3D printed perforated plates were compared. Result: 1) This study found that the 3D printed perforated plates had two resonance frequencies, which were at the low frequency and the middle high frequency, respectively. However, the sound absorption structure of 3D printed bionic wood had three resonant frequencies, which were located at low frequency, medium to high frequency and high frequency, and wood perforated plate only had low resonance frequency. 2) The angle of the perforation had effect on the sound absorption performance of the 3D printed perforated plate. At low frequency, the resonance frequency would move to the low frequency direction with the increase of the inclination angle. The peak of the sound absorption coefficient was above 0.8; in the medium to high frequency section, the angle changed with the angle of the complex hole. The resonance frequency and the peak absorption coefficient of 3D printed perforated panel were both changed, but there was no a clear law. However, the peak of sound absorption coefficient was about 0.3, and the sound absorption performance was poor. 3)The inclined angle of the hole had a great influence on the sound absorption property of the 3D printed bionic wood sound absorption structure, the sound absorption law of the low frequency section and the medium to high frequency section was basically the same as that of the 3D print perforated plate. In the high frequency section, the common vibration frequency moved to the low frequency direction with the increase of the hole angle. The peak value was above 0.8, and had a good absorption performance. Conclusion: The 3D printed bionic wood sound absorption structure with different hole angle presented good sound absorption properties at low frequency, medium to high frequency and high frequency, which were not found in the previous studies of perforated sound absorption materials. In addition, at high frequency, the resonance frequency of the 3D printed bionic wood sound absorption structure with different angle is larger, which lays a theoretical foundation for the design of the future full frequency sound absorption structure. This experiment provided a new research field for the new composite materials which can design the sound absorption frequency. It will have a good prospect in some special sound absorption environment.

Key words: wood bionic, sound absorption, Helmholtz resonator, 3D printing, hole angle