Quasi-perfect and wideband absorption with gradient non-uniform micro-slit array absorber via a hierarchical optimization method

• Published in: Applied acoustics Vol. 206; p. 109321
• Main Authors: Liao, Weiwei, Hu, Run, Xing, Guanying, Luo, Xiaobing
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2023
• Subjects: Multi-objective genetic algorithm optimization; Quarter-wavelength resonator; Transfer matrix method; Visco-thermal analysis; Transfer matrix method; Visco-thermal analysis; Quarter-wavelength resonator; Multi-objective genetic algorithm optimization
• ISSN: 0003-682X; 1872-910X
• DOI: 10.1016/j.apacoust.2023.109321

•The theoretical model based on TMM accurately predicts the absorption performance.•A hierarchical optimization method is proposed to improve micro-slit array absorber.•The width of the slit strongly corresponds to the visco-thermal effect.•Sensible arrangement of the distance between the slits is necessary. Gradient micro-slit array absorber, a kind of acoustic metamaterial, made of multiple quarter-wavelength resonators, is holding a promising future in industrial utilization due to its flexible adaptation and simple structure. However, designing a perfect and broadband absorber remains a huge challenge because of the larger number of the design parameters and complicated coupling effect between different resonators. In this study, a hierarchical optimization method is developed for gradient micro-slit array absorber. First, a prior test based on two-slit absorber is conducted using transfer matrix method (TMM) to give directions on designing a multi-slit absorber. And then an original absorber model is constructed in the range of 1000–1800 Hz. For the first step, the optimal width of the slit is obtained through the analysis of the quality factor. For the second step, the spacings between slits is optimized by maximizing absorption and minimizing the total length of the waveguide. After optimization, the absorption performance of the optimized model increased by 15.6% and the length decreased by 46% compared with the original model. Finally, the gradient micro-slit array absorber is experimentally investigated and achieves a quasi-perfect and flat absorption ranging from 1000 Hz to 1800 Hz.