Thermally bonded nonwovens are low-price substitutes for traditional textiles. They
are used in many areas including filtration, automotive and aerospace industries.
Hence, understanding deformation behaviours of these materials is required to design
new products tailored for specific applications in different areas. Because of their
complex and random structure, numerical simulations of nonwoven materials have
been a challenging task for many years. The main aim of the thesis is to develop a
computational modelling tool to simulate the effect of design parameters on
structural behaviour of low-density nonwoven materials by using a finite element
method. The modelling procedure is carried out with a parametric modelling
technique, which allows a designer to run a series of analyses with different design
parameters and observe the effects of these parameters on the mechanical behaviour
of nonwoven materials.
The thesis also presents the study of rate dependent behaviour of nonwoven fibres.
Novel test and data-interpretation procedures are proposed to determine the creep
behaviour of fibres in the nonwoven structure. Some case studies are presented to
demonstrate the effectiveness of the model.
The developed computational tool allows macro and micro-scale structural
investigation of nonwoven materials. Two additional studies are presented,
performed with the developed tool. In the first study, the effect of design parameters
on tensile stiffness of nonwovens was determined by performing numerical analyses
with various nonwoven models. In the second one, strain distribution in fibres is
studied thoroughly together with factors affecting the distribution. The models,
developed in the thesis can also be employed in further studies of nonwovens, such
as investigation of their damage and fracture behaviour.
A Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.