Deformation and energy dissipation mechanisms of needle-punched nonwoven fabrics: A multiscale experimental analysis

Abstract

Please cite this article as: Martínez-Hergueta, F., Ridruejo, A., González, C., LLorca, J., Deformation and energy dissipation mechanisms of needle-punched nonwoven fabrics: A multiscale experimental analysis, International Journal of Solids and Structures (2015), doi: http://dx. AbstractThe deformation and energy dissipation processes in a needle-punched polyethylene nonwoven fabric were characterized in detail by a combination of experimental techniques (macroscopic mechanical tests, single fiber and multi fiber pull-out tests, optical microscopy, X-ray computed tomography and wide angle X-ray diffraction) that provided information of the dominant mechanisms at different length scales. The macroscopic mechanical tests showed that the nonwoven fabric presented an outstanding strength and energy absorption capacity. The mechanical behavior was highly anisotropic although the initial fiber and knot distribution was isotropic. The load was transferred to the fabric through a set of fibers linked to the entanglement points, which formed an active skeleton. The fraction of fibers in the skeleton depended on the orientation and it was controlled by the features of * Corresponding author the entanglement points. Most of the strength and energy dissipation was provided by the progressive extraction of the fibers in the skeleton from the entanglement points and final fracture occurred by the total disentanglement of the fiber network in a given section at which the macroscopic deformation was localized. These findings provide the fundamental observations to develop microstructure-based continuum models for the mechanical behavior of needle-punched nonwoven fabrics.

Influence of fiber orientation on the ballistic performance of needlepunched nonwoven fabrics

“…The spot size was around ≈1 mm 2 and the exposure time 1 min. It should be noticed that, although the spot size was much smaller than the fiber length, the orientation distribution functions obtained with this technique were in agreement with those obtained by 3D X-ray microtomography (Martínez-Hergueta et al, 2015).…”

“…The microstructure and in-plane mechanical properties of this material were analyzed in detail in a recent paper (Martínez-Hergueta et al, 2015). The manufacturing process introduces two principal material orientations, known as machine (MD) and transverse (TD) directions, which follow the bed displacement and the perpendicular orientation, respectively.…”

“…Based on the previous results (Martínez-Hergueta et al, 2015), nonwoven specimens were deformed along TD and MD prior to the impact tests to modify systematically the initial fiber orientation distribution. To this end, rectangular samples of 500 mm in width and different heights were cut from the fabric roll by direct Joule's heating with a straight copper wire connected to a electrical power supply.…”

“…The fiber orientation distribution before and after deformation was measured by means of WAXD, following the methodology presented in Martínez-Hergueta et al (2015). The Dyneema SK75 ultrahigh molecular weight polyethylene fibers are highly crystalline and the orthorhombic crystals are oriented parallel to the fiber axis (Russell et al, 2013).…”

“…The initial studies of the structural performance of nonwoven fabrics were focused on paper (Bronkhorst, 2003;Hägglund and Isaksson, 2006;Isaksson et al, 2006Isaksson et al, , 2004 but more recent analyses have dealt with glass (Ridruejo et al, 2010), polyamide (Silberstein et al, 2012), polypropylene (Farukh et al, 2013;Jubera et al, 2014;Ridruejo et al, 2011Ridruejo et al, , 2015 and polyethylene (Martínez-Hergueta et al, 2015;Raina and Linder, 2014;Raval et al, 2013) nonwoven fabrics. These investigations found that the micromechanisms of deformation and fracture depend on the interaction of a number of factors including fiber uncurling, bond failure and fiber reorientation as well as fiber sliding and fracture.…”