Resistance end correction factor of microperforated panel made using additive manufacturing

Abstract

Fabrication of microperforated panel (MPP) using an additive manufacturing (AM) process produced imperfect perforations with an irregular shape, inconsistent size, and rough inner surface (due to burr formation). This imperfect hole condition leads to a significant deviation between measured and modeled acoustic properties. This study aims to introduce the resistance end correction factor (α) for quantifying this deviation. The MPP model’s current development excludes the irregular and inconsistent holes from the actual MPP. The improved resistance end correction factor (α) is determined based on the actual MPP samples. The MPP’s acoustic properties fabricated using AM process (3D Printing – PolyJet technology) are measured. The improved resistance end correction factor (α) is presented in surface plots for different geometrical parameters, perforation diameter (d), plate thickness (t), and perforation ratio (σ). The interpolation method is used to predict the “α” value based on the surface plot. The improved relative acoustic resistance value for the actual MPP sample with imperfect perforation condition (with recorded lowest hole roundness value at 0.207) is calculated using the predicted “α” value. Comparative results showed that the improved relative acoustic resistance determined based on the interpolated “α” agreed well with the experimental measurement results. The correlation coefficient for each comparison varied from 0.885 to 0.987. This finding is better than comparing calculated relative acoustic resistance values by using Maa’s theory and other MPP models with different proposed resistance end correction factors (α). Therefore, the proposed technique can reflect the imperfect perforation condition in actual MPP samples.

Keywords

• Sound absorption
• Micro-perforated panel
• Additive manufacturing
• Resistance end correction factor
• Interpolation method