Magnetic-responsive shape memory performance of 4D-printed acoustic metamaterials

In order to address the limitations of traditional acoustic metamaterials in sound absorption selectivity as well as their inadequate flexibility and adaptability for noise reduction, a honeycomb-thin-film acoustic absorbing metamaterial was developed in this study via 4D printing. By incorporating soft magnetic particles, the structure was enabled to obtain a remote magnetic response, thereby facilitating adaptive sound absorption capabilities. The mechanical properties, shape memory characteristics, and sound absorption performance of both the matrix material and the printed structure were independently evaluated and analyzed. The results indicated that the shape memory polymer containing 10 wt% Fe3O4 exhibited exceptional properties, with a shape fixation rate of 100%, and a shape recovery rate of 97%; the honeycomb-thin-film structure could revert to its original shape within 120 s. The tuning ranges for the two absorption frequencies (sound insulation and sound absorption) were determined to be 68 Hz and 53 Hz, respectively. This study introduces a novel approach to the development of smart acoustic materials with adaptive sound absorption properties.