Debeleac Carmen, Nechita Petronela, Nastac Silviu
Research Center for Mechanics of Machines and Technological Equipments, Engineering and Agronomy Faculty, "Dunarea de Jos" University of Galati, 810017 Braila, Romania.
Department of Environmental, Applied Engineering and Agriculture, Engineering and Agronomy Faculty, "Dunarea de Jos" University of Galati, 810017 Braila, Romania.
Polymers (Basel). 2019 Jul 23;11(7):1223. doi: 10.3390/polym11071223.
Recent studies have highlighted an innovative way to produce highly porous materials based on cellulose fibers. These studies have focused on the foam-forming process, where the cellulose fibers and other components are mixed with foam. In the authors' previous research, the foam-formed cellulose materials (FCM) were obtained by mixing a surfactant with cellulose fibers, taken from virgin pulp and recovered papers. In the present paper, the authors performed additional experimental and computational analyses in order to evaluate the sound insulation capabilities of these FCM beyond the initial impedance of tube investigations. The poroacoustics computational methodology parameters-i.e., airflow resistivity, porosity, tortuosity, viscous, and thermal characteristic lengths-were herein evaluated. This analysis was performed using both a theoretical/empirical approach from the specialized literature and an experimental investigation developed by the authors. The computational investigations were conducted in two stages: First, we evaluated the approximation of the experimentally gained normal incidence parameters, in terms of absorption and reflection, respectively, relative to the estimated ones. The second stage of analysis consists of a parametrical estimation of sound insulation characteristics concerning the incidence angle of sound hitting the porous layer. The results presented in this paper are in agreement with the computational experimental results, providing extended soundproof characteristics to the incidence angle of the acoustic field. Further, this study supplies additional information useful for future analyses regarding the influences of random geometry air inclusions into the FCM layer.
最近的研究突出了一种基于纤维素纤维生产高孔隙率材料的创新方法。这些研究集中在泡沫形成过程，即纤维素纤维和其他成分与泡沫混合。在作者之前的研究中，通过将表面活性剂与取自原生纸浆和回收纸张的纤维素纤维混合，获得了泡沫状纤维素材料（FCM）。在本文中，作者进行了额外的实验和计算分析，以评估这些FCM在管研究初始阻抗之外的隔音能力。本文评估了多孔声学计算方法参数，即气流阻力、孔隙率、曲折度、粘性和热特征长度。该分析使用了专业文献中的理论/经验方法以及作者开展的实验研究。计算研究分两个阶段进行：首先，我们分别根据吸收和反射评估了实验获得的垂直入射参数相对于估计参数的近似值。分析的第二阶段包括对声音撞击多孔层的入射角的隔音特性进行参数估计。本文给出的结果与计算实验结果一致，为声场入射角提供了扩展的隔音特性。此外，本研究提供了额外信息，有助于未来分析随机几何形状的空气夹杂物对FCM层的影响。
