Yarn Pull-out Force Research Articles

Experiments and simulations for dynamic yarn pull-out response of Kevlar® fabrics

This work presents a novel experimental method for performing dynamic yarn pull-out using a modified tensile split Hopkinson pressure bar. The pull yarn is fixed to a piezoelectric load cell, while the woven fabric specimen is displaced at pull-out velocities ranging from 22 to 32 m/s. Pull-out force, displacement, and energy absorption over time are quantified for commercially available Kevlar® KM2+ woven fabric with pull lengths L = 5 mm and 27 mm in both quasi-static (QS) and dynamic loading. Dynamic peak pull-out force increases over QS by as much as 290–460% and 170–220% for L = 5 mm and L = 27 mm, respectively, and overall energy absorption increases by 140–420% and 40–140% for L = 5 mm and L = 27 mm, respectively. In QS loading, stick–slip interactions result in forces dropping by approximately 70–80% between oscillating peaks for L = 5 mm and 30–40% between peaks for L = 27 mm, and displacements between peaks are typically 1.5 mm, corresponding to two yarn crossings or two spans. However, at dynamic rates, stick–slip stage force drops by 100% after the first and all subsequent peaks due to the dynamic release of the pull yarn from the fabric, resulting in the pull yarn passing through multiple yarn crossings. To better understand the underlying mechanisms for these observations, finite element simulations of the experiments are performed. Strain rate dependent longitudinal shear stiffness of the yarn is found to significantly affect the dynamic yarn pull-out response and explain the enhanced dynamic yarn pull-out peak force and energy absorption. While the shorter yarn of L = 5 mm experiences a more uniform loading along the entire length, non-uniform loading via progressive uncrimping is observed in the longer yarn of L = 27 mm along the length.

Revolutionizing protective materials: Ultrahigh peak viscosity through MOF-enhanced shear thickening fluid for advanced soft body armor

The incorporation of shear thickening fluid (STF) into aramid fabric has emerged as a compelling strategy to augment the protective attributes of aramid-based soft body armor. The peak viscosity of STF assumes a pivotal role in shaping the efficacy of this enhancement. In this study, we present an innovation in the design and synthesis of an ultrahigh peak viscosity STF using metal-organic framework (MOF)/SiO2 nanoparticles as the core constituents. The remarkable enhancement in peak viscosity of MOFs/SiO2-based STF, taking ZIF-8 as an exemplary MOFs material, is attributed to the pronounced interparticle contact friction facilitated by the rugged surface morphology of the ZIF-8/SiO2 nanoparticles. Therefore, ZIF-8/SiO2-based STF (62.5 wt.%) demonstrates a peak viscosity approximately 3938 times greater than that of conventional SiO2-based STF (62.5 wt.%). This extraordinary STF formulation has been successfully employed in aramid fabric-based soft body armor, resulting in a significantly advancement in protective performance. Compared to Kevlar fabric impregnated with SiO2-based STF (62.5 wt.%), the utilization of ZIF-8/SiO2-based STF (62.5 wt.%) results in substantial and scientifically significant improvements in key mechanical parameters. These include a notable 15.4 % increase in maximum stabbing force, a remarkable 29.5 % augmentation in maximum yarn pull-out force, a 24.3 % boost in maximum yarn tensile strength, and a 204.5 % enhancement in maximum fabric tensile strength. This research underscores the profound impact of synergizing ZIF-8 and SiO2 within the STF matrix, and significantly improves the protective abilities of SiO2-based STF-impregnated Kevlar fabrics, which provides a new route to design STF-impregnated ballistic fabric with high protective performance.

Investigating the effect of aligned Ag nanorods on para-aramid woven fabric and anisotropy in inter-yarn friction

Inter yarn friction, measured in terms of yarn pull-out force, is a major mechanism of energy absorption in soft body armor. Increasing inter-yarn friction of para-aramid fabric to improve ballistic performance without adding weight is challenging. This work reports the fabrication of aligned Ag nanorods (AgNRs) on the para-aramid (Kevlar) fabric surface using the glancing angle deposition technique. A single yarn pull-out test examines Kevlar fabric treatment. The AgNRs-coated para-aramid fabric retains its flexibility and weight while increasing yarn pull-out force by 130%. Anisotropy in inter-yarn friction depends on the yarn's sliding direction relative to Ag nanorod tilt direction, indicating direction-dependent yarn pull-out force. The periodic character of pull-out response post-peak force is replicated by modeling the yarn pull-out phenomenon by incorporating a mesoscale level numerical model of woven fabric. The numerical model confirms the experimental results that formation of nanorods significantly increases inter-yarn friction and pull-out force.

An impact-resistant and flame-retardant CNTs/STF/Kevlar composite with conductive property for safe wearable design

An intelligent material with shear thickening, flame-retardant and sensing properties was prepared by introducing mesoporous silica and carbon nanotubes to ionic liquids. By impregnating the conductive shear thickening fluid (STF) on Kevlar fabric and drying in an oven, CNTs/STF/Kevlar composite was obtained. Due to the rate-sensitive performance of STF, the yarn pull-out force of CNTs/STF/Kevlar increased 3–4 times compared with that of neat Kevlar, once the impregnation weight gain is 55 wt%. Furthermore, the CNTs/STF/Kevlar composite can maintain intact at 110 m/s incident velocity of bullet, whereas neat Kevlar fabric was penetrated at the same velocity, and exhibited the flame resistance as well due to the thermal insulation property of mesoporous silica and flame-retardant performance of ionic liquids. Then, CNTs/STF/Kevlar composite also performed obvious sensing characteristic due to the introducing of carbon nanotubes, and showed the application potential in the field of safe wearable equipment.

Flexible and lightweight Kevlar composites towards flame retardant and impact resistance with excellent thermal stability

The impact and thermal damage in extreme environments generally exist together. In this context, the design of safety protection materials ought to consider not only the single impact protection performance, but also thermal stability and flame resistance. In order to simultaneously achieve the impact resistance, thermal stability and flame resistance properties, a flexible and lightweight shear-hardened composite material (STF/Kevlar) was prepared by impregnating and drying shear thickening fluid (STF) on Kevlar fabric. Due to the favorable shear thickening performance of shear thickening fluid, STF/Kevlar composite material can increase the maximum yarn pull-out force of the fabric yarn from 3.3 N to 16.3 N with the impregnation weight gain of 55 wt%. Moreover, in bullet impact experiment, a single layer of STF/Kevlar fabric can nearly double the time it takes a bullet to penetrate pure Kevlar fabric. Additionally, STF/Kevlar composite material exhibits significant flame resistance as well. The limit oxygen index can reach 32 %, and after 30 min high temperature treatment at 400 °C, the composite still maintains good mechanical property and flexibility. This multi-functional composite material along with the performance of resisting both mechanical shock and thermal damage in extreme environments is expected to broadly apply in the field of lightweight protection.

Investigate the dynamic compressive (cushioning) response of 3D GFRP composites when the STF matrix base material is modified PEG

Shear thickening fluid (STF) impregnated 3D E-glass fabric is evaluated for its cushioning, yarn pull-out, and flexibility using chemically modified polyethylene glycol (PEG 400). By extending the chain length of PEG with hexamethylene diisocyanate, citric acid, and adipic acid, H-STF, C-STF, and A-STF were produced, respectively. FTIR confirmed chemical modification. PEG chemical modification boosted H-bonding between STF and particles, increasing critical viscosity compared to pure STF (P-STF). A drop-weight testing machine examined the impact time duration and maximum force of two, five, and seven-layer samples. The graph widens (increases time) as the number of layers increases and peak force decreases. The A-STF/fabric composite's impact time was 2.07, 1.59, 1.39, and 1.12 times that of neat fabric, P-STF/fabric, H-STF/fabric, and C-STF/fabric, respectively. The A-STF/fabric composite's peak force was 2.30, 1.78, 1.37, and 1.15 times that of neat fabric, P-STF/fabric, H-STF/fabric, and C-STF/fabric, respectively. P-STF/fabric, A-STF/fabric, C-STF/fabric, and H-STF/fabric required 3.55, 3.10, 2.52, and 2.14 times the yarn pull-out force of neat fabric. As a result of the PEG modifications, composites performed significantly better in energy absorption and cushion performance when compared to conventional STF impregnated fabric.

Development of a Coated Fabric Armour System of Aramid Fibre and Rubber

Ballistic impact tests were conducted on polymer-coated multi-layer fabric targets using 0.357 SIG projectiles. The effect of fatigue loading on the yarn pull-out force of coated Twaron fabrics was studied for the first time. A validated mesoscale numerical modelling approach was developed to simulate the ballistic impact. The elastomeric coating significantly improved impact resistance. The coating is stable in a wide range of ambient temperatures and performs well upon being subjected to fatigue. A coated target having 6.6% less areal density and 20% less thickness than its neat counterpart has shown similar ballistic limit velocity.

Internal friction properties of carboxylated cellulose nanofibers (CNF-C) modified aramid woven fabrics

The internal friction properties of the aramid woven fabrics modified by carboxylated cellulose nanofibers (CNF-C) were studied, in order to better investigate the effect of CNF-C on the internal friction properties of the aramid woven fabrics, the yarn pull-out force of the modified aramid fabrics were tested by single yarn pull-out test. The chemical structure and surface morphology of the aramid fibers were characterized by Fourier Transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results show that the strong hydrogen bond between CNF-C and aramid fiber and the dipole–dipole interaction between the polar groups of the fiber (such as –NH, –C = O) and hydroxyl groups are the bond mechanism. Compared with the untreated fabrics, the yarn pull-out force and fiber surface roughness of the CNF-C modified aramid fabrics are significantly improved. When the impregnation time is 0.5 h and the CNF-C concentration is 1 wt%, the yarn pull-out force reaches the maximum of 13.3 N, which is increased by 133.3% compared with the untreated aramid fabrics. The internal friction properties of the aramid woven fabrics are obviously increased by modification.

Synchronously improved thermal conductivity and tribological performance of self-lubricating fabric liner composites via integrated design method with copper yarn

The introduction of functional fillers is very important for enhancing the thermal conductivity and tribological performance of self-lubricating fabric liner composites. In present work, copper yarn was woven into hybrid Nomex/PTFE fabric via an integrated design method to fabricate self-lubricating fabric liner composites. Characterizations using thermal conductivity analyzer and tensile testing machine demonstrated that the copper fiber-reinforced self-lubricating fabric liner composites possessed a better thermal conductivity and yarn pull-out performance. The thermal conductivity and yarn pull-out force of copper yarn-reinforced self-lubricating fabric liner were 0.1814 W/m·K and 2.876 N, which increased by 78.9% and 24.8% compared with that of no-copper yarn-reinforced self-lubricating fabric liner composites, respectively. The results of wear tests indicated that the copper yarn-reinforced self-lubricating liner fabric composites exhibited preferred anti-wear properties.

Graphene Reinforced Multiphase Shear Thickening Fluid for Augmenting Low Velocity Ballistic Resistance

The impact resistance of panels made from p-aramid (Kevlar®) fabrics was improved by treating them with multiphase shear thickening fluids (STF) containing only 0.2 %, 0.4 % and 0.6 % graphene nanoplatelets. The multiphase STFs showed enhanced peak viscosity than their pure counterpart, signifying better shear thickening. The yarn pull-out force increased (25 %) in multiphase STF treated fabrics as compared to that of pure STF treated fabrics. The dynamic impact resistance also improved (6.5 % to 19.7 %) in multiphase STF treated fabrics. Finally, multiphase STF treated fabric panels demonstrated superior ballistic resistance, against low velocity ballistic impact (165±10 m/s) in terms of either energy absorption or number of bullets stopped.

INVESTIGATION OF THE EFFECT OF SHEAR THICKENING FLUID AND FABRIC STRUCTURE ON INTER-YARN FRICTION PROPERTIES IN TWARON FABRICS

It is known that shear thickening fluids increase the energy absorption capacity of high performance fabrics. For this reason, soft body armors were produced by impregnating shear thickening fluids recently on high performance fabrics. In this study, it is aimed that examine the effects of shear thickening fluid and fabric structure on the inter-yarn friction properties of para-aramid fabrics with different properties. Fumed silica was dispersed in polyethylene glycol to produce shear thickening fluid. Twaron 200 and Twaron 460 para-aramid fabrics with different properties such as threads number (105x105 and 67x67), areal density (200 gr / m2 and 460 gr / m2) and linear density (930 and 3360 Dtex) were impregnated with shear thickening fluid. It was observed that both of shear thickening fluid impregnated fabrics had higher yarn pull-out force than neat fabrics due to inter-yarn friction. When shear thickening fluid impregnated fabrics were compared to maximum yarn pull-out force; Twaron 200 and Twaron 460 fabrics requires approximately 3 times and 9 times more force to pull-out the yarn in comparison to the neat fabric respectively. In this study, it has been observed that the positive effects of shear thickening fluid impregnation on energy absorption of Twaron fabrics depend on structural parameters such as threads number, areal density and linear density.

Deciphering the structure-induced impact response of ZnO nanorod grafted UHMWPE woven fabrics

Ultra-high molecular weight polyethylene (UHMWPE) fibres, a popular choice for armour applications, have low coefficient of friction which is not favourable for good impact resistance. An attempt has thus been made in this study to increase the inter-yarn friction in UHMWPE woven fabrics by in-situ ZnO nanorod (Z-NR) grafting. The inter-yarn friction, characterised by yarn pull-out force, increased after Z-NR grafting in all fabrics irrespective of their structural variations. For all fabrics woven with 1350 denier yarn and loose fabrics woven with 400 denier yarn, Z-NR grafted fabrics outperformed their neat counterparts in terms of impact energy absorption and peak force. However, for tightly woven fabrics of 400 denier yarn, the impact energy absorption decreased in comparison to that of neat fabrics. The fabric structure induced role of Z-NR grafting was hence found to be a promising approach to augment the inter-yarn friction and consequently impact resistance of UHMWPE fabrics.

Enhancement of Yarn Pull-Out Force of Para-Aramid Fabric at High Speed by Dispersion and Phenolic Anchoring of MWCNT on the Fiber Surfaces in the Presence of Surfactant and Ultrasonic Process

Enhancement of Yarn Pull-Out Force of Para-Aramid Fabric at High Speed by Dispersion and Phenolic Anchoring of MWCNT on the Fiber Surfaces in the Presence of Surfactant and Ultrasonic Process

Effect of finishing chemicals on tearing strength of plain-woven cotton fabric

Purpose This paper aims to assess the relationships amongst the tearing strength of fabrics after each chemical processing stage and after finishing of plain-woven cotton fabric. An effort has been made to study the effect of different finishing chemicals (tear improver) and their different concentrations on the high-density fabric tear strength and its sub-component with respect to the co-efficient of friction value of yarns for all the fabric samples. It also aims to establish a statistical model for prediction of tear strength with identified parameters as yarn–yarn friction co-efficient, yarn pullout force and single yarn strength. Design/methodology/approach In case of woven fabrics, it cannot be assumed that only yarn friction plays the role in deciding fabric-tearing strength. Whether the static or kinetic frictions need to be considered or the linear or capstan frictions have to be analyzed, to incorporate the results of friction analysis in the tearing behavior, need to be assessed. In the present work through a fabrication of yarn–yarn friction measurement, under a synchronized slow speed as that of actual fabric tearing (50 mm/min), has been carried out. After each wet processing stage, surface characteristics of yarns have been changed. Surface of yarns becomes smoother after finishing and rough after dyeing, which affects the co-efficient of friction of yarns, accordingly. Findings After each wet processing stage, the surface characteristics of yarns are changed. Surface structure of yarns becomes smooth after finishing and rough after dyeing, which affects the co-efficient of friction of yarns. For all the fabrics, the weft-way tearing strength is always higher than warp-way tearing strength. It is also observed that yarn pullout force is not the only responsible factor for tearing strength of such fabric. It is because of the combined action of yarn–yarn friction, yarn pullout force and single yarn strength for a given structure. Research limitations/implications A more extensive investigation with respect to concentration as well as further variety of chemicals requires to be identified for the optimum concentration level for each chemical. A mathematical model based on the three parameters as yarn–yarn co-efficient of friction, yarn pullout force and yarn strength for all woven fabric structure to achieve optimum strength level has been established which could be further extended for each fabric structures. Practical implications The problem has been identified from the day-to-day exercise of the commercial textile industry. The whole of the sample preparations have been done in the industry by using commercial machines under standard industrial conditions. The findings have been discussed and suitably introduced in the industry. Originality/value The whole of this paper has been unique in idea origination, sample preparation and execution of tests. The findings are very important for the researchers as well as for textile industry.

Deconstructing the role of shear thickening fluid in enhancing the impact resistance of high-performance fabrics

The role of shear thickening fluid (STF) in enhancing the impact resistance of STF treated fabrics has long been debated. There is a need to clarify whether the dominant mechanism of energy absorption is shear thickening (dilatancy) or friction enhancement. This study establishes that the inherent shear thickening behaviour of STF has a decisive role to play other than just improving the yarn to yarn friction. Kevlar® 363 and Kevlar® 802 F fabrics were treated with STF comprising of 65% (w/w) silica and 35% polyethylene glycol (PEG) 200. Three monodispersed STFs and nine bi-dispersed STFs were prepared from three different particle sizes of silica (100 nm, 300 nm and 500 nm) and their binary mixtures keeping the mass fraction of silica constant (65%). Rheological results showed that STFs prepared form monodispersed silica resulted in higher peak viscosity as well as discontinuous shear thickening. However, bi-dispersed STFs prepared by mixing two different sizes of silica particles, in general, showed lower peak viscosity and continuous shear thickening. In both the fabrics (Kevlar® 363 and Kevlar® 802 F), yarn pull-out force, a measure of yarn to yarn friction, did not show much difference among the fabrics treated with different STFs. However, low velocity impact tests clearly showed enhanced performance in terms of energy absorption and peak force in case of fabrics treated with monodispersed STFs. This correlation between shear thickening and impact resistance conclusively establishes that the former has a dominant role in enhancing the latter of high-performance fabrics.

An experimental investigation of the yarn pull-out behavior of plain weave with leno and knitted insertions

Yarn–yarn sliding force plays a vital role in absorbing impact energy for plain fabrics. This paper reports the methods and results of an investigation on the mechanisms that enable higher yarn pull-out force of woven fabrics with the incorporation of lenos and knits. The experimental results suggested that the insertion of leno lines on plain weave gives an approximately 20% increase in junction rupture force over the original plain construction. With knitted structures inserted, the structure-modified fabrics showed a junction rupture force up to about 15 times higher than simple plain weave. It was even found that the yarns failed rather than pulled out in multiple yarn pull-out tests. This is because knitted structures tend to become self-locked and consequently restrict yarn displacement when subjected to external loading. This investigation reports a method to increase the frictional force between the warp and weft yarns based on textile technologies. It is expected that the results obtained could provide some useful information for the engineering design of flexible ballistic protection systems.

Structure induced effectiveness of shear thickening fluid for modulating impact resistance of UHMWPE fabrics

The structural parameters of woven fabrics play a crucial role in determining its impact resistance performance. Conventionally, treatment with shear thickening fluid (STF) has been found to increase the impact energy absorption capacity of fabrics. However, the findings of the current study present a new perspective, and suggest that the effect of STF treatment is favorable based on the structural integrity of woven fabrics. Plain woven fabrics with different fabric sett (threads per inch) were produced using ultra-high molecular weight polyethylene (UHMWPE) yarns of 400 denier and 1350 denier linear density. These fabrics were then treated with STF (65% w/w) made from silica particles (100 nm) dispersed in polyethylene glycol i.e. PEG (200 Mw) and subsequently evaluated for yarn pull-out force and impact energy absorption. The increased yarn pull-out force, at all levels of yarn linear density and fabric sett, implies that STF treatment considerably increases the inter-yarn friction. However, increased yarn to yarn friction is not necessarily beneficial in terms of impact energy absorption and rather becomes detrimental for fabrics made from finer yarns (400 denier) beyond a particular fabric sett.

The effect of graphene on the yarn pull-out force and ballistic performance of Kevlar fabrics impregnated with shear thickening fluids

The ballistic performance of Kevlar fabric impregnated with different shear thickening fluids (STFs) were investigated at various impact velocities. The SiO2 nanoparticle based STFs were reinforced with graphene and showed a significant increase in viscosity and shear thickening efficiency compared to pure STF. Ballistic experiments were performed on fabric treated by different STFs, and different failure modes including yarn slipping, extraction, and breakage in shear failure were obtained. To better understand how different STFs affect ballistic performance, single yarn pull-out tests were also carried out to examine the shear strength and friction between the interlocking yarns of fabric treated with STF. The results showed that STF reinforced with graphene is better at preventing the yarns from slipping, and the single yarn pull-out force is almost 5 times more than pure STF. Moreover, reinforced STF also has a significant influence on the ballistic limit and energy absorption of Kevlar fabrics. And the increased amplitude of energy absorption is almost 20% more than the pure STF/Kevlar load case. Combining with the energy absorption and different failure modes, the effect of STF on the failure mechanism of neat/treated fabric was also discussed.

Effects of fabric construction and shear thickening fluid on yarn pull-out from high-performance fabrics

Yarn pull-out is one of the major modes of fabric failure during an event of impact. In this article, the effects of weave and fabric sett on yarn pull-out force have been investigated for untreated and shear thickening fluid (STF) treated p-aramid fabrics. Further, the effect of different fluid treatments on yarn pull-out behavior has been analyzed using p-aramid and ultra-high molecular weight polyethylene (UHMWPE) fabrics. For all levels of fabric sett, plain woven fabrics exhibited higher yarn pull-out force compared to twill, matt and satin weaves. STF impregnation increased the yarn pull-out force considerably for p-aramid and UHMWPE fabrics and this was found for all the weaves in the case of the former. However, increase in fabric sett beyond a threshold level caused yarn breakage before yarn pull-out in case of STF-treated plain woven p-aramid fabrics. Yarn pull-out force was found to have good association with the energy absorption by the high-performance fabrics during low-velocity impact (6 m s–1). The normalized yarn pull-out force was higher for two consecutive yarns than for two yarns with a single gap.

Effects of sample dimensions on pull-out properties of woven fabric structures

The aim of this study was to understand the effects of fabric sample dimensions on pull-out properties of fabric weaves. Polyester woven fabrics were used to conduct the pull-out tests. A yarn pull-out fixture was developed and data generated from this research. Yarn pull-out forces depend on sample dimensions, fabric density, fabric weave, and number of pulled ends in the fabric. Results showed that multiple and single yarn pull-out forces of long samples were higher than those of short samples, and the multiple yarn pull-out force was higher than that of the single yarn pull-out force, and dense fabric has high pull-out force. Plain fabric weave showed high single and multiple pull-out forces compared to ribs and satin fabric weaves. The regression model could be used in this study as a viable and reliable tool. This research could be valuable for development of multifunctional fabrics in technical textile applications.