A decoupled and programmable on-demand design concept for acoustic-mechanical multifunctional structures

The potential engineering applications of acoustic-mechanical multifunctional structures surpass those of traditional acoustic or mechanical metamaterials. The vast potential in various sectors, including aerospace, marine, and machine manufacturing, highlights the promising growth trajectory of these structures. This paper presents a novel design concept that includes a decoupled design method for the separate design of gas domains, solid domains, and materials, as well as an on-demand programming method for structural sizing. A case of structural performance index with stable sound absorption at a low-frequency broadband, a high load-bearing or repeatable loading ability is illustrated via the decoupled design, while the relationship between hole diameter, cavity length, and sound absorption performance is obtained from the programmable on-demand design. The envisioned construct enables on-demand tuning of the acoustic performance in the frequency range of 50–1600 Hz and can reduce labor and time costs through deep neural networks (DNNs). Furthermore, plastic nylon (PA) and thermoplastic polyurethane (TPU) are strategically incorporated to ensure a strong load-carrying capacity of acoustic metamaterials. The findings demonstrate that utilizing PA material in the structure significantly enhances its specific energy absorption capacity by a factor of five. Meanwhile, the use of TPU material as the base material not only allows for reusing the structure but also achieves a high resilience level approaching 100 %.