Lightweight additively manufactured TPMS sound absorbers: Boosting performance at low frequencies with dual-microperforated panels

• Proposes a novel lightweight sandwich structure (CMPP-DSS) that integrates dual-microperforated panels with a Diamond-TPMS core. • Monolithic fabrication via SLM ensures high specific stiffness and strength for multifunctional load-bearing applications. • Achieves a significant 302 Hz low-frequency shift in sound absorption peak compared to conventional designs. • Reveals the acoustic coupling mechanism behind the enhanced broadband energy dissipation. • Provides practical design guidelines by quantifying the effects of key geometric parameters. Owing to their smooth surfaces, highly interconnected pore architectures, and mathematically tunable geometric features, triply periodic minimal surfaces (TPMS) have garnered significant attention as a promising framework for designing porous acoustic structures. Although increasing the panel thickness and number of cell layers can enhance the mid-to-low frequency sound absorption of TPMS-based porous sandwich structures, such improvements often come at the expense of increased overall mass. In this study, a composite micro-perforated plate diamond sandwich structure (CMPP-DSS) is proposed. By systematically varying key parameters—including micro-perforated plate thickness, cell layer count, and perforation rate—the acoustic performance of the CMPP-DSS is evaluated and compared with that of a conventional micro-perforated plate diamond sandwich structure (MPP-DSS) under identical structural conditions. Experimental results demonstrate that the CMPP-DSS exhibits superior sound absorption capabilities in the mid-to-low frequency range compared to the MPP-DSS, under the same cavity depth and structural parameters. Specifically, through structural optimization, the peak sound absorption frequency was shifted downward by 302 Hz while maintaining a peak absorption coefficient above 0.95. Furthermore, increasing the parameter l 1 significantly promotes the migration of the absorption peak toward lower frequencies, though this is accompanied by a corresponding narrowing of the bandwidth. These findings underscore the potential of CMPP-DSS as an ultra-lightweight multifunctional solution that integrates load-bearing, energy absorption, and acoustic performance. This work provides valuable insights for the development of lightweight, high-strength, and broadband sound-absorbing structures targeting mid-to-low frequency applications.