Inverse notch sensitivity: Cracks can make nonwoven fabrics stronger

Ridruejo, Álvaro; Jubera, Rafael; González, C.; LLorca, J.

doi:10.1016/j.jmps.2015.01.004

Cited by 39 publications

(21 citation statements)

References 22 publications

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“…Most of the energy is dissipated by frictional sliding and plastic deformation of the fibers (in the case of polymeric fibers) without significant fiber fracture. Interestingly, it has been recently shown that the failure strength of polypropylene nonwoven fabrics can be enhanced above of that found in smooth specimens in the presence of deep notches (Ridruejo et al, 2015). This inverse notch sensitivity effect is triggered by the rapid re-orientation of the fibers perpendicular to the notch plane during deformation, which enhances the load carrying capability of the material across the central ligament.…”

Section: Introductionmentioning

confidence: 99%

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

Martínez-Hergueta

Ridruejo

González

et al. 2015

International Journal of Solids and Structures

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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.

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Section: Introductionmentioning

confidence: 99%

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

Martínez-Hergueta

Ridruejo

González

et al. 2015

International Journal of Solids and Structures

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“…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.…”

Section: Introductionmentioning

confidence: 99%

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

Martínez-Hergueta

Ridruejo

Gálvez

et al. 2016

Mechanics of Materials

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a b s t r a c tThe influence of the initial fiber orientation distribution on the ballistic performance of a needlepunched nonwoven polyethylene fabric was analyzed. To this end, ballistic tests were carried out in specimens pre-deformed along the machine or the transverse directions and the influence of pre-deformation on the fiber orientation was measured by means of wide angle X-ray diffraction. It was found that pre-deformation along the machine direction (the soft orientation of the fabric) led to more isotropic in-plane mechanical response and to a marked increase in the specific ballistic limit and in the energy dissipated by unit weight while the opposite behavior was found after stretching the fabric along the transverse direction. These differences were accompanied by changes in the penetration mechanics from extensive fiber pull-out to slippage between fibers in the network. These results highlight how the nature of the nonwoven microstructure (connectivity of the entanglement points and fiber orientation distribution) can be tailored to improve the impact performance.

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“…Fibres parallel to the loading direction (MD) in the vicinity of such areas accommodated deformation and increased the resistance to damage propagation in the direction perpendicular to the loading [34]. In the case of fibre-to-fibre bonds in a fibrous network, the tensile strength of the notched specimens might be also improved by fibre bridging [35]. The constituting fibres of samples demonstrated ductile behaviour and some of them could be stretched to double lengths.…”

Section: Failure Model and Failure Analysismentioning

confidence: 99%

“…Spatial non-uniformity of fibrous networks causes variations in localisation of strain and failure [23]. A specific microstructure of nonwovens can even enhance tensile strength in presence of a notch [24]. To the authors' knowledge, only limited research pertaining to micro-mechanisms and mechanical behaviour of fibrous materials containing localised damage is available in the literature.…”

Section: Introductionmentioning

confidence: 99%

Deformation and damage of random fibrous networks

Sozumert

Farukh

Sabuncuoğlu

et al. 2020

International Journal of Solids and Structures

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1 HIGHLIGHTS  Damage and fracture mechanisms of fibrous networks are investigated.  A combined experimental and numerical (finite-element) study is implemented. Effects of notch shape on deformation localization and damage evolution are studied. A notch in fibrous networks does not cause a significant increase in localized strain. AbstractFibrous networks are encountered in various natural and synthetic materials. Typically, they have random microstructures with complex patterns of fibre distribution. This microstructure, together with significant (in many cases) stretchability of such networks, results in a nontrivial load-transfer mechanism, different from that of continuous media. The aim of this study is to investigate evolution of local deformation, damage and fracture processes in fibrous networks. In order to do this, together with extensive experiments, discontinuous finiteelement (FE) models with direct incorporation of microstructural features were developed using a parametric approach for specimens with various dimensions and different types of notches. These models, mimicking a microstructure of the selected fibrous network, were loaded by stretching along a principal direction. Discontinuous FE models provided data not only on a global response of the specimens but also on levels of stresses and strains in each fibre, forming the network. An effect of a notch shape on evolution of fibre strains as well as mechanisms and patterns of damage was investigated using experimental data and simulation results, assessing also toughness of specimens. Strain distribution over selected paths were tracked in notched specimens to quantify strain distributions in the vicinity of notch tips. The growth and patterns of local damage due to axial stretching obtained in advanced numerical 1 Corresponding author (Vadim V. Silberschmidt): Wolfson School of Mechanical, Electrical and Manufacturing Engineering3 simulations with the developed FE models demonstrated a good agreement with experimental observations.

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Inverse notch sensitivity: Cracks can make nonwoven fabrics stronger

Cited by 39 publications

References 22 publications

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

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

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

Deformation and damage of random fibrous networks

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