The Impact of Additive Manufacturing on the Acoustic Performance of Novel Porous Materials

Abstract

Commonly used conventional acoustic porous materials suffer from a limited operational frequency range and great dependency of the sample thickness on their performance. For this reason, acoustic metamaterials have caught the eye of the scientific community with their ability to manipulate and absorb soundwaves despite their subwavelength dimensions. These novel acoustic materials are especially of interest for aerospace and automotive industries. Industrially relevant design tools are required to unlock the potential of these materials and the development of these tools requires benchmark problems. This work analyzes how the additive manufacturing process influences the acoustic performance of a periodic porous acoustic material. To answer this question, samples of a benchmark material were fabricated using selective laser melting with a 0.03 mm layer height. An optical microscope, a confocal microscope and computerized tomography scanner were used to examine manufactured specimens and provide insight into their surface topology. Numerical models of the structure were created. The computational results were compared with the experimental values. A combination of modelling strategies are investigated to incorporate features of the additive manufacture in the prediction of the acoustic behaviour. The observed mismatch between them can only partially be explained by the presence of the surface roughness. This study emphasizes the need to take into account more aspects of the additive manufacturing process when designing acoustic materials.