Acoustic modeling of three-dimensional-printed fibrous sound absorbersa).

In this study, an analytical model was developed to predict the sound absorption performance of fibrous absorbers fabricated using an extrusion-based three-dimensional (3D) printing method. The proposed model employs geometric design parameters, including the average fiber diameter and the horizontal and vertical fiber separations, to calculate the porosity, static airflow resistivity, tortuosity, and viscous and thermal characteristic lengths. These transport parameters are then used within the Johnson-Champoux-Allard semiempirical formulation to predict the normal incidence sound absorption coefficient. The analytical model was validated by comparing the calculated properties with those obtained using the finite element-based hybrid numerical modeling method and those estimated through direct and indirect experimental measurements. Finally, by using the validated analytical model, the effect of each geometrical design parameter on the sound absorption performance of the 3D-printed fibrous absorbers was investigated, revealing that the absorption behavior is primarily controlled by the static airflow resistivity and showing that high absorption peaks and a broadband absorption profile can be achieved by adjusting the three geometrical parameters. This study highlights the potential of 3D printing to fabricate fibrous sound absorbers with tailored acoustic properties, offering a promising solution for advanced noise control materials.