Acoustics-mechanics synergistic sheet Diamond-TPMS/polyimide interpenetrating composite structure: broadband sound absorption and high load-bearing characteristics

To address the limitations of traditional acoustic materials characterised by ‘high absorption but low load-bearing capacity, and high load-bearing but poor absorption,’ this study focuses on developing a multifunctional integrated structure that combines broadband high-efficiency sound absorption with excellent load-bearing performance. Based on additive manufacturing technology, three types of structures were designed and fabricated using sheet Diamond-TPMS as the skeleton: the pristine sheet Diamond-TPMS structure, the micro-perforated sheet Diamond-TPMS structure, and the sheet Diamond-TPMS/polyimide interpenetrating composite structure. The regulation mechanism of volume fraction on their sound absorption performance was systematically investigated. The results show that the sheet Diamond-TPMS/polyimide interpenetrating composite structure exhibits optimal comprehensive performance at a volume fraction of 20%. Its average sound absorption coefficient reaches 0.76, representing significant improvements of 55.1% and 72.7% compared to the pristine sheet Diamond-TPMS and micro-perforated sheet Diamond-TPMS structures, respectively. Moreover, it achieves efficient broadband sound absorption across the 450–6400 Hz frequency range. This performance advantage stems from the synergistic mechanism of porous dissipation and structural resonance. Ultimately, the composite structure successfully integrates acoustic and mechanical properties, achieving ultra-broadband sound absorption (relative bandwidth of 166.3%) while maintaining high load-bearing capacity, providing a reliable solution for the design of next-generation multifunctional acoustic materials.