Fractal Approach to Sound Absorption Behavior in Nonwoven

Sound absorption property in nonwovens requires specifying relationship with structural characteristic. Fractal approach seems to be a potentially useful tool to describe hierarchical systems and is suitable to link the structure and acoustic properties of nonwovens. In this paper, the pore area fractal dimension of nonwoven is calculated, and the sound absorbing behavior of nonwoven is measured. Correlation between the fractal dimension of nonwovens and the acoustic absorption property is also studied. The results indicate that the acoustic absorption coefficient grows linearly with increasing pore area fractal dimension, while the absorption peak moves towards lower frequency.

I. Introduction

Many researchers have studied the sound absorption behavior of nonwovens [1]–[4], which is closely related to the geometry of nonwovens. Understanding structural parameter sensitivities for nonwovens can be extremely useful for acoustical design optimization (cost, weight and acoustical effectiveness) [5]. However, nonwovens are heterogeneous systems composed of the contact points between fibers, the fiber lengths between the contact points, and the void space enclosed by the adjacent fibers[6], so acoustical design optimization of nonwovens is complex due to inter-dependencies of structural parameters.