The Importance Of A Variable Fibre Packing Density In Modelling The Tensile Behaviour Of Single Filament Yarns

A model able to reproduce the tensile response of single continuous-filament yarns based on parameters derived from geometrical descriptors is presented in this paper. Samples of yarns made of polyester and aramid fibres were scanned at rest using X-ray microtomography, allowing a detailed identification of their fibre orientation distributions for different twists. The variation of the fibre packing density along with yarn extension was characterized by means of additional scans carried out during tensile tests. An analytical model of the tensile response of these yarns, based on the orientation distribution function and the evolution of the packing density identified from microtomography is proposed and validated against experimental results, with good agreements.