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This study explores the use of additive manufacturing, specifically stereolithography (SLA), to create porous acoustical materials with precise pore geometries for aircraft engine noise reduction. Unlike traditional methods like foaming and fiber-spinning, SLA allows for exact control over pore shapes. Three triply periodic minimal surface (TPMS) pore designs were investigated: split-P, lidinoid, and diamond. These structures were designed through implicit modeling and made from polymeric resin. Their sound absorption capabilities were tested under normal incidence in a two-microphone impedance tube to examine how porosity influences their acoustic performance. Findings revealed unique sound absorption profiles for each geometry, which can be modified by adjusting porosity. Additionally, the static flow resistivity was measured using a raylometer, where results showed that flow resistance is a key factor in their absorption efficiency. Among the three samples, the split-P geometry shows superior sound absorption. This preliminary research highlights the potential of using tailored TPMS geometries in acoustic liners for effective noise control in aerospace applications.
Ciletti et al. (Fri,) studied this question.