Fabrication of Micro-Perforated Panel (MPP) sound absorbers using Digital Light Processing (DLP) 3D printing technology

The fabrication of Micro-Perforated Panels (MPPs) still constitutes a challenge to the acoustic materials industry because it usually requires expensive manufacturing techniques to obtain holes of submillimetre size. In this context, the rise of additive manufacturing or 3D printing (3DP) technologies over the last years has paved the way for the design and development of new materials at the microscopic scale. Among these, Digital Light Processing (DLP) technology emerges as an excellent option due to its advantages in terms of printing speed and higher accuracy when compared to traditional additive manufacturing technologies. This work demonstrates the capacity of DLP technology to fabricate MPPs and explores its design possibilities by using different exposure times in the manufacturing process to attain different hole sizes. To this end, several MPP specimens were fabricated and tested when used as a resonator system in an impedance tube setup to determine their sound absorption performance, the experimental data showing a good agreement when compared to predictions obtained using the Maa model. Preliminary results highlight the potential capabilities of DLP and encourage its use in the design stage of these acoustics resonator systems.