Optimized membrane-type acoustic metamaterials for alleviating engineering fatigue damage via lightweight optimization

Currently, most acoustic metamaterials have been designed for ultra-thin sizes to achieve perfect and low-frequency sound absorption or insulation performance, with less attention paid to fatigue damage in practical engineering applications. In this study, a lightweight optimal design for the membrane-type acoustic metamaterial is proposed for alleviating fatigue damage. Normally, the elastic membrane was decorated with several metal platelets for tuning the natural frequencies in the membrane-type acoustic metamaterial. However, the sound waves may cause the fatigue damage to the membrane in the long-term engineering applications. The fatigue damage caused by sound can be significantly alleviated by the proposed lightweight optimization for the membrane-type acoustic metamaterial. To maintain the low-frequency sound absorption performance while achieving the lightweight purpose, a multi-objective particle swarm optimization algorithm is applied to the lightweight optimization of the proposed structure. The fatigue simulation results showed that the corresponding minimum fatigue life is increased by 10.27% using the proposed lightweight approach. Furthermore, the experiments using the dual port measurement without backing were conducted to investigate sound absorption performance of the proposed structure before and after lightweight optimization. Both of theoretical and experimental results showed that the average sound absorption coefficients of the proposed structure after optimization are 41.6% and 22.2% larger than those before optimization, respectively. The total weight of the proposed structure after optimization is 25.9% lighter than that before optimization.