Number Of Fabric Layers Research Articles

Ballistic Impact of Twaron CT709® Plain Weave Fabrics

The ballistic impact of Twaron CT709® plain weave fabrics is studied using a three-dimensional fabric model. The model is developed by treating each individual yarn as a continuum, and the time-dependent yarn behavior is phenomenologically described using a three-dimensional linear viscoelastic constitutive relation. A user subroutine VUMAT for ABAQUS/Explicit is compiled to incorporate the constitutive behavior. By using the newly developed model, a parametric study is carried out to analyze the effects of various parameters on the impact behavior of the fabrics, which include impact velocity, inter-yarn friction, and the number of fabric layers. The simulation results obtained include bullet residual velocity, fabric deformation and damage pattern, kinetic energy of the system, fabric strain energy, and frictional dissipation energy. The residual velocities predicted by the current model correlate well with existing experimental data, and the parametric study leads to the determination of the optimal number of fabric layers and the optimized level of inter-yarn friction that are needed to achieve the maximum energy absorption in the fabrics at specified impact velocities.

Experimental determination of bending behavior of multilayered and multidirectionally-stitched E-Glass fabric structures for composites

The aim of this study was to experimentally determine the bending behavior of developed multilayered multistitched E-Glass preform structures. For this reason, a bending rigidity test instrument based on the cantilever test principle was used. A bending rigidity test was conducted on all developed multilayered multistitched E-Glass preform structures. Yarn linear density and fabric density influenced the bending rigidity of single layer E-Glass fabric. The single layer fabric's bending rigidity depended on the off-axis angle orientations in the fabric plane. On the other hand, the bending rigidity of the multilayered unstitched E-Glass fabric structure depended on the number of fabric layers. The bending rigidities of the multilayered four directional hand and machine stitched E-Glass preform structures were high compared with one and two directional hand and machine stitched E-Glass preform structures. The bending rigidities of all heavy (6 step/cm) machine stitched E-Glass preform structures were high compared with light (2 step/cm) machine and hand (1 step/cm) stitched E-Glass preform structures. In addition, the bending rigidities of all developed multilayered hand and machine stitched E-Glass preform structures were higher than those of unstitched preform structures due to stitching. In addition, the multilayered multistitched preform structures showed a low order of bending curvatures compared with the multilayered unstitched preform structures. The results indicated that the number of stitching directions and stitching steps substantially affected the bending rigidity of the developed preform structures. Stitching yarn type was also a parameter for the bending behaviorof the multistitched preform structures. It was considered that the unstitched fabric structure could be easily formed whereas the directional stitched E-Glass preform structure became stiff and could not be easily formed.

Experimental study of dynamic air permeability for woven fabrics

Dynamic permeability is relevant to textile applications subjected to fluid/gas flow under high pressure, such as automotive airbags, wearable airbags and parachute fabrics. Dynamic permeability can be determined when a porous medium is tested under transient pressure conditions. This paper utilizes a reliable approach to measure and characterize dynamic permeability for woven fabrics. The experimental principle is based on the ideal gas law and the non-linear Forchheimer equation. Compared with static permeability measured under a constant low pressure, the dynamic permeability is an intrinsic property determined by change of fabric geometry and structure due to a high-pressure load. The pressure-induced deformation is identified, including effects on fiber and yarn arrangement, yarn porosity and fabric thickness. The level of deformation is a function of the number of fabric layers and initial pressure drop. The experimental results show that the dynamic permeability is higher than the static permeability for loose fabric, while it is lower for tight fabrics. For tight fabric, more fabric layers and a lower initial pressure can reduce the difference between the static and the dynamic permeability. Analytical models are used to explain and predict both static and dynamic permeability.

Evaluation of anti-stabbing performance of fabric layers woven with various hybrid yarns under different fabric conditions

Various types of special fibers are used for human body protection, mostly in the form of fiber-reinforced composites. These composites are made of special fibers and matrix resin; however, they are often not comfortable for the wearer due to the lack of flexibility and air permeability. This study focuses on an evaluation of human body protective performance against stabbing for various special fibers such as aramid, basalt, and steel fibers, being utilized in cotton hybrid forms. These hybrid forms are designed to improve wearer comfort, while maintaining adequate anti-stab resistance. Specimens prepared with various fabric densities are tested in terms of anti-stabbing performance, according to the NIJ standard. In addition, we investigate the influence of factors such as fiber type, the number of fabric layers, fabric weight, and fabric density on anti-stabbing performance. Results show that the penetration depth of the impactor, which punctures and protrudes through the specimens, decreases with the number of layers, the thickness, and the mass of the armor sample; however, these factors have different relationships according to the material type. Consequently an objective evaluation of anti-stabbing performance is needed. We suggest an anti-stabbing index that can be applied as a criterion to evaluate the antistabbing performance of various specimens woven with special fibers under different fabric conditions. Using the new index, anti-stabbing performances of various specimens can be compared and raw material and fabric conditions that offer the most efficient anti-stabbing performance can be selected.

Experiment-based thermal model for permeable clothing systems under hot air jet impingement conditions

An experiment-based, two-medium thermal model was developed to evaluate the thermal response and protective performance of permeable clothing systems under hot air jet impingement conditions. The clothing systems consisted of single- or double permeable fabric(s) and air volume between the fabrics and an enclosure wall (solid surface with an embedded heat sink of constant-temperature) to mimic human skin. Two types of permeable fabrics were considered for this study: (i) NOMEX III A as a thermal protective fabric and (ii) Cotton/Spandex as a commodity fabric. The predicted results from the model were well compared with the experimental results from a previous work. A parametric study was conducted using various jet impingement conditions and design variables of the protective clothing such as the number of fabric layers, air leakage rate, air gap thickness, and fabric type. It was concluded from the parametric study that the permeable clothing with multiple layers of fabric, less air leakage, and thicker air gap had better thermal protective performance under hot air jet impingement conditions.

Bending behavior of multilayered and multidirectional stitched aramid woven fabric structures

The aim of this study was to experimentally determine the bending behavior of developed multilayered and multistitched ballistic structures which could affect the comfort for the wearer. For this reason, the bending rigidity test was conducted on all developed multilayered and multistitched ballistic structures after the impact test. Fabric density and crimp ratio influenced the bending rigidity of single layer fabric. On the other hand, the bending rigidities of multilayered and multistitched ballistic structures depended on the number of fabric layers and stitching directions. Generally, multilayered four directional stitched ballistic structures showed the highest bending rigidity compared to the two and one directional stitching. Multilayered and multistitched ballistic structures showed high bending rigidity compared to multilayered and unstitched ballistic structures. This indicated that the number of stitching directions affected the bending rigidity of the developed ballistic structures. In addition, multilayered and multistitched structures showed a low order of bending curvatures compared to the multilayered unstitched structure. On the other hand, after all structures were impacted by one type of projectile but varied speeds, multistitched structures had low conical depth compared to those of the unstitched structures. This was because stitching increased the bending rigidity of the ballistic structures and reduced the structural deformation to the out-of-plane direction. It could not, however, be easily formed and it could decrease the ballistic comfort to the wearer.

EFFECT OF THREAD STRUCTURE ON TENSION PEAKS DURING LOCK STITCH SEWING

Abstract A dynamic sewing tension study was carried out with a tension probe on sewing threads with different structures, physical and tensile characteristics in a single needle lock stitch sewing machine. The needle thread recorded four major tension peaks corresponding to events occurring during sewing; bobbin thread withdrawal, stitch tightening, needle piercing the fabric and tightening of the needle thread around the shuttle, among which stitch tightening caused the maximum tension for all threads. Polyester filament and spun polyester threads exhibited the highest and lowest tightening tension, respectively. Multiple regression analysis showed that pre-tension and elastic modulus show positive influences while tex, bending, rigidity and compressibility of threads show negative effects on tension peaks during tightening and needle piercing. Sewing speed shows a positive impact only on the tension peak due to needle piercing. Pre-tension showed a prominent influence on tension peaks on all threads while the number of fabric layers failed to show any effect.

The Properties of Agricultural Waste Particle Composite Reinforced with Woven Cotton Fabric

The production of particle composites using agricultural waste materials is an area of significant research interest. in general the properties of agricultural waste particle composites are considered to be inferior to those of commercial particleboards. In this study, the inclusion of woven cotton fabric has been used to overcome this drawback. Particle composites were manufactures from coconut shell- and rubberwood-particles using urea formaldehyde as a binder and combined with woven cotton fabric to reinforce the material. The fabricated agricultural waste particle composites were then evaluated with respect to the effect of the number of fabric layers in the composite structure and the inherent effect on the mechanical (flexural and impact strength) and physical (water absorption and thickness swelling) properties. Agricultural waste particle composites without any reinforcement were used as control samples in this study. The test results indicate that the flexural and impact properties of particle composites reinforced with woven cotton fabric are better than those for the control samples. It was also determined that both the mechanical and physical properties improve with increasing fabric layers, except with respect to thickness swelling.

Optimization of the procedure to burn textile fabrics by cone calorimeter: Part I. Combustion behavior of polyester

AbstractThe aim of this study was the optimization of cone calorimeter to determine the burning behavior of textile fabrics. In particular, the combustion behavior of commercial polyester textile fabrics with varying densities was studied in terms of time to ignition (TTI), heat release rate (HRR), and relative peak (pkHRR) were monitored. Reproducibility and repeatability of the data have been verified by the influence of instrument variable including incident heat flux, the temperature of ceramic backing pads and retaining grid used during sample mounting as well as sample weight (as the number of fabric layers), the density of textiles, and the relative humidity. A low reproducibility has been obtained when a wire grid was not used to stabilize samples during the tests. The effects of these variables on TTI and pkHRR were observed. Copyright © 2010 John Wiley & Sons, Ltd.

A neural network model for prediction of strength loss in threads during high speed industrial sewing

In this paper artificial neural network (ANN) model has been designed to predict the strength loss in threads during high speed industrial sewing. Four different types of threads (Mercerized cotton, polyester staple spun, polyester-cotton core spun and polyester-polyester core spun) were taken for the study. The other input parameters include thread linear density, fabric area density, number of fabric layers, stitch density and needle size. In order to reduce the dependency of the results on a specific partition of the data into training and testing sets, a four-way cross validation tests were performed, i.e. total data was divided into training and testing set in four different ways. The predicted tenacity loss was correlated to the experimental tenacity loss and correlation coefficient between the actual and predicted tenacity loss obtained. It was observed that the neural network system is able to predict the tenacity loss of threads after sewing with good correlation and less average error. The relative contribution of each parameter to the overall prediction of the tenacity loss was studied by carrying out the sensitivity analysis of the test data set. The results of sensitivity analysis show that thread type is the most important input parameter followed by thread linear density, number of fabric layers, fabric area density, needle size and the stitch density.

Study of heat transfer through layers of textiles using finite element method

PurposeThe purpose of this paper is to present the results of a study on heat transfer through a textile assembly consisting of fabric and air layers based on a theoretical model capable of dealing with conductive, convective and radioactive heat transfer.Design/methodology/approachQuantificational results were given out by the aid of finite element (FE) analysis software MSC MARC Mentat.FindingsSignificant findings through this paper include the change in heat flux against time and the transit temperature distribution at the cross‐section of the fabric assembly. The size of the air gaps has a significant influence on the heat transfer. The balance heat flux drops by 40 per cent when the air gap increases from 2 to 10 mm. The influence of the air gap tends to become smaller as the air gap is further increased. The number of fabric layers in the textile assembly has a noted influence, more so when the ambient temperature is lower. Comparisons between the theoretical and tested results show a good agreement.Originality/valueThis paper has established a new method for clothing comfort study by making use of a general purpose FE method software package.

Variable cavity volume tooling for high-performance resin infusion moulding

This article describes the research carried out by Warwick under the BAE Systems/EPSRC programme ‘Flapless Aerial Vehicles Integrated Interdisciplinary Research - FLAVIIR’. Warwick's aim in FLAVIIR was to develop low-cost innovative tooling technologies to enable the affordable manufacture of complex composite aerospace structures and to help realize the aim of the Grand Challenge of maintenance-free, low-cost unmanned aerial vehicle manufacture. This article focuses on the evaluation of a novel tooling process (variable cavity tooling) to enable the complete infusion of resin throughout non-crimp fabric within a mould cavity under low (0.1 MPa) injection pressure. The contribution of the primary processing parameters to the mechanical properties of a carbon composite component (bulk-head lug section), and the interactions between parameters, was determined. The initial mould gap ( di) was identified as having the most significant effect on all measured mechanical properties, but complex interactions between di, n (number of fabric layers), and vc (mould closure rate) were observed. The process capability was low due to the manual processing, but was improved through process optimization, and delivered properties comparable to high-pressure resin transfer moulding.

Effect of Process and Machine Parameters on Changes in Tensile Properties of Threads during High-speed Industrial Sewing

The dynamic, thermal, bending and abrasive loading of thread during sewing process has a negative influence on the properties of sewing threads. In this study, the individual and interactive effect of the number of fabric layers, stitch density and needle size on the loss in tenacity, breaking elongation and initial modulus of four types of thread has been studied using Box-Behnken design. Response surface regression equations of loss in tensile properties on the above parameters were developed. The predicted equations agreed well with the experimental data. Contrary to the general expectation, the loss in tenacity and breaking elongation was found to decrease initially or remain unchanged as the number of fabric layers increased. Initial modulus loss decreased with the increase in number of fabric layers for all threads. Except for cotton thread, stitch density did not show any significant influence on tenacity and breaking elongation loss. As the needle size increased, the loss in tenacity and breaking elongation increased for all polyester threads, whereas these properties remained unchanged for cotton thread. Analysis of variance was carried out to find out the contribution of parameters in loss in tensile properties. The number of fabric layers was found to have the highest contribution on tenacity and breaking elongation loss of cotton threads, whereas needle size contributed substantially to the loss in these properties of polyester threads.

Microfibril-Based Estimates of The Ballistic Limit of Multilayered Fabric Shielding

An expression relating the dominant mechanisms for the energy loss of a projectile, as it penetrates a multilayered ballistic fabric shield, is developed. The relation is a function of the projectile mass, initial velocity and fabric microscale properties, such as microfibril stiffness and critical stretch. Using the derived expression, the number of fabric layers needed to stop a projectile is determined. The analytical result compares quite well to experiments.

Novel approach to textile design for barriers against electromagnetic radiation

Human-friendly barriers against microwave radiation are designed using non-woven multiple layers of natural (flax) fibres, as well as flax and polypropylene fibre blends, with the split-ring resonators implanted so as to allocate the barrier properties in the pre-determined frequency band (X-band is selected for its applications in traffic radars and telecommunication). Oscillator model is proposed for determining the ring resonance frequency. The band of non-transmission up to ∼40 dB is observed. The band is found to shift depending on the flax and polypropylene contents in the blend, the distance between the ring centres, and on the number of textile layers.

Textile-reinforced mortar (TRM) versus FRP as strengthening material of URM walls: in-plane cyclic loading

In this study the application of a new structural material, namely textile-reinforced mortar (TRM), as a means of increasing the load carrying capacity and deformability of unreinforced masonry walls subjected to cyclic in-plane loading is experimentally investigated. The application of externally bonded TRM is considered in this work as an alternative method to the application of fiber-reinforced polymers (FRP). Hence, the effectiveness of TRM overlays is evaluated in comparison to the one provided by FRPs. Medium-scale tests were carried out on 22 masonry walls subjected to in-plane cyclic loading. Three types of specimens were used: (a) shear walls; (b) beam-columns; and (c) beams. The parameters under investigation included the matrix material (mortar versus resin), the number of textile layers and the compressive stress level applied to shear walls and beam-columns. Compared with their resin-impregnated counterparts, mortar-impregnated textiles may result in generally lower effectiveness in terms of strength, but in much higher in terms of deformability. From the results obtained in this study it is believed that TRMs hold strong promise as a solution for the structural upgrading of masonry structures under in-plane loading.

Low Velocity Impact Damage Tolerance Studies on Glass-Epoxy Laminates - Effects of Material, Process and Test Parameters

An effort has been made to study the effects of variable incident impact energy and laminate thickness (obtained by varying the number of fabric layers at constant moulding pressure and also by varying the pressure for a fixed number of fabric layers), on the low velocity impact damage tolerance of GFRP composite laminates (woven E-glass fabric in a room temperature cure epoxy system LY556/HY951). Repeated drop tests were conducted using an in-house built drop weight impact tester. Number of drops to failure (Nf), was considered as the impact damage tolerance index. Correlations between Nf and composite material parameters (fiber weight fraction - Wf, laminate thickness - t, number of fabric layers - L) and a test parameter (incident impact energy - E) were found out and the bounding limits for these were defined. Critical values of impact energy (Ec) and laminate thickness (tc) were defined (for the particular resin - hardener system chosen for the study) which can quite possibly be used as designer’s guidelines. A new ratio, (t/Wf), was introduced for the study of composite systems where both fiber weight fraction and laminate thickness get affected upon alteration of a process parameter (the pressure - P as in this case).

On the effect of stacked fabric layers on the stiffness of a woven composite

Abstract Most micromechanical models for stiffness prediction of woven composites assume independence of the Q-matrix on the number of fabric layers in the composite. For example, the moduli of single and 10 layer composites are assumed to be equal in the case when all layers have the same in-plane orientation. Although this statement is likely to be true for isotropic materials or even for unidirectional laminated composites, it may not be valid in some cases of woven composites. This paper contains experimental and theoretical investigations of plain weave carbon fiber/polyester composites. Specimens with one single and eight layers of fabrics are tested and observable differences of mechanical properties are obtained. The theoretical part of this article consists of derivation and application of several micromechanical models on these particular composites. The use of those simplified models finally allows us to find the main mechanisms which cause the observed effects.

Removal of phenolic compounds from aqueous solution by activated carbon cloths

Granular activated carbon (GAC) is easily used in water or wastewater treatment in order to remove organic micropollutants. Recently, a new presentation of activated carbon has been developed: fibrous activated carbon in the form of cloth or felt. This work investigates the adsorption onto activated carbon cloths (ACC) of various phenolic compounds from aqueous solution. Experiments were carried out in batch reactors with two ACCs (called CS 1501 and RS 1301) and their performances were compared with those of GAC. Initial adsorption kinetic coefficients were higher with fibers than with granules due to the direct connection of micropores to the external surface of fibers. Adsorption isotherms were also performed and modelized by Langmuir and Freundlich equations. Adsorption capacities were similar or higher with ACCs than with GAC. The behaviour of the ACC CS 1501 was also studied in a dynamic reactor. The breakthrough curves allowed the determination of high maximum adsorption capacities, 117 mg.g−1 for phenol. Pressure drops in ACC beds were measured and the influence of various parameters was shown: the activation step, the number of fabric layers, the space between two layers.

Removal of phenolic compounds from aqueous solution by activated carbon cloths

Granular activated carbon (GAC) is easily used in water or wastewater treatment in order to remove organic micropollutants. Recently, a new presentation of activated carbon has been developed: fibrous activated carbon in the form of cloth or felt. This work investigates the adsorption onto activated carbon cloths (ACC) of various phenolic compounds from aqueous solution. Experiments were carried out in batch reactors with two ACCs (called CS 1501 and RS 1301) and their performances were compared with those of GAC. Initial adsorption kinetic coefficients were higher with fibers than with granules due to the direct connection of micropores to the external surface of fibers. Adsorption isotherms were also performed and modelized by Langmuir and Freundlich equations. Adsorption capacities were similar or higher with ACCs than with GAC. The behaviour of the ACC CS 1501 was also studied in a dynamic reactor. The breakthrough curves allowed the determination of high maximum adsorption capacities, 117 mg.g−1 for phenol. Pressure drops in ACC beds were measured and the influence of various parameters was shown: the activation step, the number of fabric layers, the space between two layers.