From Shear to Sound: Mechanics–Acoustics Mapping of TPMS Lattices

Triply periodic minimal surface (TPMS) lattices offer a framework for integrating load‐bearing capacity and functional response within a single architected material. However, existing studies have largely focused on compression and treated mechanical and acoustic properties independently. Here, we map the coupled mechanical and acoustic performance of TPMS architectures across relative densities of 15%–75%, combining simulations and experiments, including a dedicated shear testing methodology. We show that commonly used descriptors, including Gibson–Ashby scaling and load‐aligned solid fraction, fail to predict shear and bulk stiffness, despite their proven validity for the same TPMS under compression. This reveals a fundamental limitation of existing models when extended to shear, where stiffness is governed by connectivity, cross‐sectional heterogeneity, and complex strain distribution pathways that are not captured by either the Gibson–Ashby scaling or the load‐aligned solid fraction. Acoustically, a transition occurs at 25% relative density: below this threshold, all architectures exhibit broadband absorption governed by viscothermal losses, whereas at higher densities, constrictions generate coupled neck–cavity elements that induce distributed resonance. The peak absorption scales with cavity‐to‐neck ratio. Density grading tunes absorption while preserving overall mass and thickness. These results establish TPMS lattices as a platform for multifunctional, load‐bearing acoustic materials.