Optimization Design of Acoustic Black Hole and Micro-Perforated Plate Composite Structure

Abstract By combining theoretical analysis, finite element simulation, and experimental measurement, and utilizing powerful computer simulation technology, an optimization design method has been explored to improve the sound absorption performance of structures composed of micro perforated plates and acoustic black holes. First, based on the transfer matrix method, the total transfer matrix of the composite structure of acoustic black holes and micro-perforated plates is established. Through MATLAB programming, the reflection coefficient curve of the structure is calculated and compared with the finite element simulation results. Then, the simulated annealing algorithm, a computer optimization technique, was used to establish an optimization model for the structure of the acoustic black hole tube, aiming to ensure the high-frequency sound absorption performance as much as possible, and to improve the low-frequency sound absorption performance by changing the size of each cavity of the acoustic black hole. Finally, the micro-perforated plate is placed at the entrance of the main pipe to further optimize the structure to expand the effective sound absorption bandwidth and improve octaves of the reflection coefficient below 0.2. The results show that by optimizing the radius of the acoustic black hole cavity, the lower limit frequency of the effective absorption band obtained by the transfer matrix method is expanded from 1136 Hz to 239 Hz, and the broadband effective absorption in the range of 239-2030 Hz is realized. After adding a micro-perforated plate to the front end of the acoustic black hole, the lower limit frequency obtained by the transfer matrix method is expanded from 239 Hz to 228 Hz, and the upper limit frequency is expanded from 2030 Hz to 2318 Hz. The bandwidth is expanded by 16.7 % and has 3.35 octaves. The lower limit frequency obtained by the finite element method is expanded from 264 Hz to 240 Hz, and the upper limit frequency is expanded from 1875 Hz to 2225 Hz. The bandwidth is expanded by 23.2 % and has 3.21 octaves. These results not only validate the effectiveness of optimization design methods, but also demonstrate the enormous potential of computer simulation and optimization algorithms in acoustic structure design, providing new ideas and directions for future acoustic engineering research.