Study on Acoustic and Mechanical Properties of AlSi7Mg/TPU Porous Interpenetrating Phase Composites

The rapid development of high-end equipment has created stringent requirements for multifunctional integration in materials. However, traditional porous materials have faced a fundamental trade-off between lightweight characteristics and mechanical and acoustic performance. To address this challenge, a design and fabrication method for interpenetrating phase composites (IPCs) based on triply periodic minimal surface (TPMS) structures was proposed. The effects of porosity, unit cell size, and structural type on the performance of porous structures were systematically investigated. TPMS frameworks were fabricated from AlSi7Mg alloy using laser powder bed fusion (LPBF). These frameworks were then combined with thermoplastic polyurethane (TPU) via a foaming infiltration process to create the AlSi7Mg/TPU IPCs. Acoustic and compression tests were performed using an impedance tube and a universal testing machine. The results indicated that, compared to unfilled TPMS structures, the IPCs exhibited a shift in the first peak acoustic absorption coefficient to lower frequencies, an increase (1.59 = fold) in the average acoustic absorption coefficient within the 500–6300 Hz range, and a significant enhancement (35.58 fold) in the average normal incidence transmission loss (TL). Under quasi-static compression, the plateau stage was sustained over 60% strain, and the energy absorption capacity increased by a factor of 3.56. This research provides a technical reference for developing multifunctional materials for aerospace and other acoustic applications.