Comprehensive analysis of acoustic properties of cellulose nano fibers absorbers: experimental and FEM-based mathematical modeling evaluation

This research investigates the acoustic properties of cellulose nanofiber-based (CNF) foam sound absorbers. Samples with varying thicknesses (10, 20, and 30 mm) and air gap widths (10, 20, and 30 mm) were fabricated and analyzed using experimental and mathematical methods. Experimental analysis utilized an impedance tube according to ISO 10534-2 standards, while mathematical modeling employed the Johnson-Champoux-Allard (JCA) and Attenborough models via Finite Element Numerical Method in COMSOL software. Results indicate CNF foams as promising alternatives to synthetic fibers, with absorption coefficient increasing with sample thickness. Notably, air gaps behind the samples demonstrated similar performance enhancement to thicker materials. Average absorption coefficients ranged from 0.52 to 0.60 for various air gap widths. Layering techniques during fabrication further improved acoustic performance, with average absorption coefficients of 0.33, 0.43, and 0.52 for thicknesses of 10, 20, and 30 mm, respectively. The values of NRC (Noise Reduction Coefficient)-SAA (Sound Absorption Average) corresponding to thicknesses of 10-, 20-, and 30-mm stand at 0.25–0.26, 0.45–0.45, and 0.59–0.59, respectively. Modeling showed the JCA model accurately predicted acoustic behavior, with a 0% error rate for SAA and NRC, while the Attenborough model exhibited an 18.64% error rate for a thickness of 3 cm.