Acoustic Characterisation and Modelling of Multi-Fibrous Nonwovens

Sharma, Neha

Acoustic Characterisation and Modelling of Multi-Fibrous Nonwovens

Sharma, Neha

Authors

Neha Sharma

Contributors

Olga Umnova
Supervisor

Abstract

This thesis explores the theoretical, numerical, and experimental approaches for nonwoven materials with the intent of quantifying, testing, and characterising the acoustic performance of currently available products and to guide the development of a novel range of nonwovens. The literature review reveals that there is ample knowledge of technical textile driven functionality, but there is paucity in the understanding of nonwoven material interaction with sound waves. The acoustic response of nonwovens is an exigent research area, particularly for optimising the acoustic capability of technical textiles and sustainable materials.
The present work reviews existing theoretical and computational modelling approaches for fibrous materials and their limitations. Firstly, models for sound propagation around mono-disperse fibres were formed using three modelling approaches: regression based empirical models, theoretical methods adapting the analytical models for cylinders and numerical models. The current work extends the modelling capability to study bi-disperse fibres using two alignments: adjacent or tandem and staggered cases. Further work has been carried out to explore the interaction of poly-disperse fibres for symmetric and asymmetric arrangements.
Both dual and cluster fibre models have been assessed for realising the acoustic influence of three key parameters: anisotropy, inter-fibre spacing and blend ratio. Numerical models developed for single, dual and cluster fibre cases have been validated for the selected nonwoven samples and have generally shown good agreement with the experimental sound absorption measurements. Finally, the acoustic effect of some additional parameters of nonwovens arising due to textile enhancements and sustainable choices have been presented as practical applications. Key findings of nonwoven behaviour are reported in the thesis that demonstrate a realistic possibility of novel nonwoven product outcomes.
This work has been based on the author’s contribution towards industrial research projects carried out as Knowledge Transfer Partnerships, funded by the Innovate UK.