作者机构：
[Chen, Guohao; Wang, Zhiqiao] Univ South China, Sch Civil Engn, Hengyang 421001, Peoples R China.;[Zhang, XY; Zhang, Xiaoyang] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
通讯机构：
[Zhang, XY ] U;Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
关键词：
thermal effect;locally resonant;finite element method;tunable bandgap;defect states;waveguide
摘要：
Based on the finite element method, the modulation of the bending wave bandgap and bending waveguide of locally resonant phononic crystal (PnC) plates via a thermal environment is investigated. First, the finite element model of the PnC subjected to a thermal field is introduced; then, the modulation behavior of the bending wave bandgap of the PnC under thermal flux is illustrated; finally, the tunable waveguide of the bending waveguide of the PnC supercell is proposed to be realized by setting up a local heat source. The results show that the injected heat flux causes the PnC unit cell band structure to move toward the low-frequency region while the relative bandgap width increases. The linear defect state of the PnC supercell structure is realized by introducing a local heat source, and a new band is added to the bending wave bandgap of the original supercell. The transmission loss of the bending wave is significantly higher than that of the bending wave bandgap of the supercell in the frequency interval of the linear defect of the supercell, and the frequency response vibrational modes of the supercell structure validate the feasibility of the thermally controlled bending waveguide. This method provides a flexible and efficient control strategy for the frequency tuning of the bending wave bandgap and waveguide.
摘要：
This study proposes an acoustic metamaterial featuring a Helmholtz resonator–spiral metasurface (HRSM) to effectively achieve low-frequency broadband sound absorption. A theoretical model is developed to predict the HRSM’s sound absorption performance, and it is validated by numerical simulations and acoustic impedance tube experiments. Results indicated that the spiral metasurface of the HRSM extended the depth of the Helmholtz resonator cavity compared to the Helmholtz resonator, causing the first sound absorption peak of the HRSM to shift to a lower frequency. Additionally, the spiral channels of HRSM impeded wave propagation in the second layer, shifting the second sound absorption peak to a lower frequency, as compared to the double layer Helmholtz resonator. Optimal design was explored further in terms of diameters and lengths of the necks in the upper and lower layers of the HRSM, by taking advantage of the additive nature of absorption peaks generated by distinct units. With a structural thickness of 52 mm, the HRSM achieved closed to 90 % continuous absorption within the frequency range of 270–580 Hz, demonstrating excellent broadband absorption capabilities. This study offers an effective feasible methodology for designing sub-wavelength low-frequency broadband absorption structures.
This study proposes an acoustic metamaterial featuring a Helmholtz resonator–spiral metasurface (HRSM) to effectively achieve low-frequency broadband sound absorption. A theoretical model is developed to predict the HRSM’s sound absorption performance, and it is validated by numerical simulations and acoustic impedance tube experiments. Results indicated that the spiral metasurface of the HRSM extended the depth of the Helmholtz resonator cavity compared to the Helmholtz resonator, causing the first sound absorption peak of the HRSM to shift to a lower frequency. Additionally, the spiral channels of HRSM impeded wave propagation in the second layer, shifting the second sound absorption peak to a lower frequency, as compared to the double layer Helmholtz resonator. Optimal design was explored further in terms of diameters and lengths of the necks in the upper and lower layers of the HRSM, by taking advantage of the additive nature of absorption peaks generated by distinct units. With a structural thickness of 52 mm, the HRSM achieved closed to 90 % continuous absorption within the frequency range of 270–580 Hz, demonstrating excellent broadband absorption capabilities. This study offers an effective feasible methodology for designing sub-wavelength low-frequency broadband absorption structures.
