Acoustic performances of triply periodic minimal surfaces fabricated by additive manufacturing: Effects of cell geometry, aspect ratio, and wall thickness

This work evaluates the acoustic absorption of additively manufactured Triply Periodic Minimal Surfaces (TPMS), focusing on Gyroid and Diamond geometries with varying aspect ratios (AR) and wall thicknesses (WT). Samples were characterized using two and four-microphone impedance tubes, and a test bench for measuring air flow resistivity. Results show that Diamond structures with AR = 0.5 and WT = 0.5 mm achieved almost complete sound absorption (α = 99) at 1185 Hz with a 30 mm sample thickness, outperforming Gyroid geometries. Lower AR values enhanced sound absorption at mid-frequency by increasing tortuosity and decreasing flow resistivity. The non-acoustic parameters retrieved from measurements were used for an inverse characterization based on the Johnson Champoux Allard model. The fitting proved to be very good. These findings provide practical design criteria for optimizing TPMS-based acoustic absorbers in industrial noise control.