Numerically modeling the sound absorption behavior of 3D printed fibrous absorbers

Abstract

Recently, we have demonstrated the feasibility of using extrusion-based additive manufacturing methods to fabricate fibrous sound absorbers [1]. Here, we investigate the feasibility of predicting the sound absorption behavior of such structures by extracting their geometry-based transport properties using the hybrid, multiphysics modeling approach. The acoustical transport properties are calculated by modeling the fibrous unit cell and solving three boundary value problems over the representative elementary volume of the periodic fluid domain. Our results show that the absorption predictions obtained using the as-designed unit cell significantly differ from the experimental measurements obtained using conventional two-microphone impedance tube tests. Further investigations conducted using an optical microscope reveal that while the printed fiber diameter remains uniform over its central portion, the fiber diameter decreases drastically near the fiber root. Finally, we show that incorporating these geometrical differences within the model improves computational predictions and accounts for the deviations between the numerical and experimental absorption coefficients. [1] Johnston W, Sharma B. Additive manufacturing of fibrous sound absorbers. Additive Manufacturing. 2021 May 1;41:101984.