Advanced acoustic design: 3D printed thermoplastic folded core sandwich structures with porous materials and microperforations for enhanced sound absorption

This study introduces a novel sound-absorbing sandwich structure with a folded core, created through 3D printing technology, to address the challenge of weak sound absorption in the low-frequency range in sound absorption materials (SAMs). The structure comprises chopped carbon fiber–dispersed thermoplastic polyamide (CF-PA), continuous carbon fiber (CCF) filaments, and polyurethane (PU) foam coated with graphene oxide (GO). Simulation studies revealed that optimized structural parameters and microperforation diameters resulted in enhanced sound absorption coefficient (SAC) of 99 % or more at 1250 Hz, within the low-frequency range (160–1600 Hz). The GO-coated PU foam SAMs demonstrated excellent sound absorption performance measured in the high-frequency range (1600–6000 Hz), achieving 99 % SAC at 2400 Hz. Furthermore, the fabricated folded core structure exhibited outstanding sound absorption performance, achieving SAC of 99 % at 732 Hz measured in the low-frequency (160–1600 Hz) band and 99 % at 600 Hz, showcasing broad absorption capabilities measured in the high-frequency band (160–6000 Hz). Additionally, a flatwise compression test on the structure filled with GO-coated PU foam demonstrated a 32 % improvement in compressive load, indicating the structure's versatility for various applications.