From unit--cell Geometry to Effective Acoustic Properties of Periodic Lattice Structures

Periodic lattice structures enabled by additive manufacturing provide a versatile platform for lightweight, mechanically robust, and tunable sound-absorbing materials. Yet predicting their effective acoustic behavior remains challenging, since key non-acoustical parameters in equivalent-fluid models are often obtained from dedicated measurements or computationally intensive inverse procedures. In this work, a geometry-informed framework is developed to directly relate unit-cell descriptors of simple cubic truss lattices to effective acoustic properties and sound absorption performance. Closed-form expressions are derived for porosity and characteristic lengths, and a compact regression model is constructed for high-frequency tortuosity based on geometry-derived data. Airflow resistivity, which cannot be reliably determined from geometry alone, is selected through a voting-based strategy that evaluates candidate literature models against finite element benchmarks across multiple lattice configurations. The resulting simplified equivalent-fluid model enables rapid prediction of normal-incidence absorption and is validated against both full finite element simulations and impedance tube measurements of 3D-printed samples. Over a wide range of unit--cell sizes and relative densities, the framework captures resonance frequencies and overall absorption trends. Roughness-resolved simulations further reveal the significant influence of manufacturing-induced surface features on acoustic response, highlighting the importance of as-fabricated geometry in predictive modeling.