Mechanical analysis of bi-component-fibre nonwovens: Finite-element strategy

Abstract

a b s t r a c tIn thermally bonded bi-component fibre nonwovens, a significant contribution is made by bond points in defining their mechanical behaviour formed as a result of their manufacture. Bond points are composite regions with a sheath material reinforced by a network of fibres' cores. These composite regions are connected by bi-component fibres -a discontinuous domain of the material. Microstructural and mechanical characterization of this material was carried out with experimental and numerical modelling techniques. Two numerical modelling strategies were implemented: (i) traditional finite element (FE) and (ii) a new parametric discrete phase FE model to elucidate the mechanical behaviour and underlying mechanisms involved in deformation of these materials. In FE models the studied nonwoven material was treated as an assembly of two regions having distinct microstructure and mechanical properties: fibre matrix and bond points. The former is composed of randomly oriented core/sheath fibres acting as load-transfer link between composite bond points. Randomness of material's microstructure was introduced in terms of orientation distribution function (ODF). The ODF was obtained by analysing the data acquired with scanning electron microscopy (SEM) and X-ray micro computed tomography (CT). Bond points were treated as a deformable two-phase composite. An in-house algorithm was used to calculate anisotropic material properties of composite bond points based on properties of constituent fibres and manufacturing parameters such as the planar density, core/sheath ratio and fibre diameter. Individual fibres connecting the composite bond points were modelled in the discrete phase model directly according to their orientation distribution. The developed models were validated by comparing numerical results with experimental tensile test data, demonstrating that the proposed approach is highly suitable for prediction of complex deformation mechanisms, mechanical performance and structure-properties relationships of composites.

Effect of areal density and fiber orientation on the deformation of thermomechanical bonds in a nonwoven fabric

“…Many mechanical models have been proposed to describe the material behavior of the thermomechanically bonded nonwovens. In the models for nonwovens, the bonds are treated as rigid bodies or as composites whose properties are calculated from bicomponent virgin fiber properties . The rigid body assumption on the bonds leads to inaccurate predictions due to the significant strain experienced by the bonds .…”

Analysis of the deformability of flax-fibre nonwoven fabrics during manufacturing

“…If all these studies mainly deal with the tensile mechanical behaviour of composites manufactured from nonwoven reinforcements, the identification of the mechanical properties of dried nonwoven preform has not been widely studied [14]. Experimental analysis conducted by Farukh et al [14,15] showed significant tensile strain abilities in the 50% range. They also showed that strong anisotropy in mechanical property could be observed because of the non-uniform orientation distribution of the fibres within the nonwoven structure.…”

Nonwovens modelling: a review of finite-element strategies

“…To overcome these shortcomings, a parametric finite-element strategy based on direct introduction of fibres into the model was suggested in Sabuncuoglu et al (2012Sabuncuoglu et al ( , 2013a and further developed by Farukh et al (2012Farukh et al ( , 2013aFarukh et al ( , 2013bFarukh et al ( , 2014. Such a parametric model has the advantage to implement the changes in parameters such as the number and orientation distribution of fibres, size, shape and pattern of bond points easily.…”

“…fibre rotation and stretching) (Farukh et al, 2013a;Jearanaisilawong, 2008), viscoelastic mechanisms (e.g. fibre relaxation or creep) and additional irreversible mechanisms (e.g.…”