Investigating ballistic impact on fabric targets with gripping yarns

The purpose of the research is to investigate the fabric structure (with gripping yarns) in influencing ballistic performance aiming to improve the ballistic performance of the currently used body armour materials. Thirteen different fabrics having gripping yarn were designed along fabric warp and/or weft directions. Their ballistic performance in terms of energy absorption has been studied and comparisons made among the single layered fabrics and between the two double layered fabrics, as well as to the conventional used a plain woven fabric for both cases. It was found that fabrics with gripping yarns have improved fabric ballistic performance. The inter-jointed two-layer fabric performed better than the un-jointed two-layer fabric, and it showed a 16.6 % increase in the energy absorption. The implication of the research is that body armour can be made lighter without reducing ballistic impact performance by using gripping yarns.     

Investigating ballistic impact properties of woven kenaf-aramid hybrid composites

In this study, the ballistic impact performance of woven kenaf-Kevlar hybrid and non-hybrid composites against fragment simulating projectiles (FSPs) was investigated. All the composites were prepared using the hand lay-up technique, method, followed by static load compression. The hybrid composites consist of Kevlar fabric and woven kenaf layers. The results obtained indicate that the energy absorption, ballistic limit velocity (V ₅₀) and failure behaviour of the composites during the impact event were affected by the woven kenaf hybridisation. The additional kenaf layers in hybrid composites resulted in the increase in composites thickness and areal density, thus increased the energy absorption (14.46 % to 41.30 %) and V ₅₀ (5.5 % to 8.44 %). It was observed that the hybrid composites failed through a combination of fibre shear, delamination and fibre fracture in the impacted surface, woven kenaf-Kevlar interface and rear surface respectively. Although the specific energy absorption was lower for the hybrid composites, further investigations need to be carried out to utilise the great potential natural fibres.     

Improving the impact resistance of p-aramid fabrics by sequential impregnation with shear thickening fluid

A simple and effective method for impregnation of p-aramid (Kevlar^®) fabric with shear thickening fluid (STF) has been developed in this research. Kevlar fabric was impregnated with STF in two stages in a sequential manner. Three levels of pressure (0.5, 1 and 2 bar) were used in each stage of impregnation. It was observed that impact energy absorption by Kevlar fabrics, impregnated with STF in this newly developed method, increased significantly as compared to untreated Kevlar fabrics and Kevlar fabrics treated with STF in conventional way (single step impregnation). Better results were obtained when the first impregnation pressure was higher than that of the second, even with same combination of pressures. Such fabrics also showed a much higher STF add-on (~18 %) as compared to that of fabrics impregnated in single step (3-5 %). Low velocity ballistic tests also confirmed the advantages of the new method as sequentially impregnated fabric showed 124.8 % and 24.4 % increase in impact energy absorption compared to untreated and STF impregnated Kevlar fabrics in single step, respectively.     

Stab-resistant property of the fabrics woven with the aramid/cotton core-spun yarns

Aramid fibers are mainly used for industrial applications and human body protection against ballistic threats. But they are used mostly in forms of composites. And fabrics woven with a high yarn count offer a moderate protection performance against the knife stabbing due to the low shear strength. This research is focused on investigating the effect of the aramid core-spun yarns on the stab resistance of the woven fabrics. With the aramid core-spun yarns with core to sheath weight ratio of 1 to 2.5 the armor specimens having different fabric densities were prepared and the knife edge impact test was conducted. On the impact energy of the knife at the level 1 according to the NIJ standard, the drop tower test results demonstrated that fabric density of the armor specimens affected the stab resistance significantly. The penetration depth of the impactor through the armor specimens was associated with the thickness and mass of the armor sample in different ways. Being the stab resistance introduced by considering the penetration depth of the impactor via thickness and weight per surface area, the effects of the fabric conditions on the anti-stabbing property could be systematically analyzed and turned out that there was an optimal level of the fabric density, showing the most effective stab resistance.     

Investigation on acoustic behavior and air permeability of struto nonwovens

This work deals with the study of acoustic performance of struto nonwovens and their relation to fabric air permeability. In order to achieve the objective of the research, sound absorption coefficient of struto nonwovens was determined via impedance tube method, the average value of sound absorption coefficient (α?) was calculated. Air permeability of struto nonwovens was examined by using FX3300 Textech Air Permeability Tester. Results showed that struto nonwoven exhibited good absorption ability at frequency bands 3000-6400 Hz while it was ineffective for frequency lower than 3000 Hz. Struto nonwovens with high GSM and fabric thickness showed better acoustic performance and lower air permeability. It was observed that α? was inversely proportional to air permeability, with correlation coefficient 0.95. It was concluded that air permeability can be used as a criterion of sound absorption behavior of struto nonwovens. A lower air permeability suggests a better sound absorption performance for struto nonwoven fabrics.     

Ballistic-resistant stainless steel mesh compound nonwoven fabric

The energy of impact must decay and be transmitted after a bullet is shot through a ballistic-resistant cloth with a laminate structure. A rigid net structure transmits the impact stress to reduce the breakage of the material in the direction perpendicular to the fabric after the impacting of a projectile. This work combines the rigid net structure of stainless steel mesh with two layers a needle-punched polyamide nonwoven fabric to create a sandwich-like laminate structure. A compound fabric that is composed of a stainless steel mesh and polyamide nonwoven fabrics is placed in multi-layer Kevlar fabrics, and the buffer effect is measured by performing a dropping weight impact test and a bullet-shooting test. The specifications of the stainless steel mesh and the order of placement of the compound fabrics are varied to show the effect of these parameters on the energy of fracture propagation and the buffer effect of the multi-layered Kevlar compound fabric that includes a layer of compound fabric that is made of stainless steel mesh and polyamide nonwoven fabrics. In this study, the compound fabric replaces several layers of Kevlar unidirectional fabric, to be used to reduce the cost of bulletproof vests without reducing ballistic resistance.     

Determination of optimal system parameters to measure bending property of fabric based on the CHES-FY system

The main content of the paper is to determine the optimal system parameters to measure bending property of fabric based on the Comprehensive Handle Evaluation System for Fabric and Yarn (CHES-FY). Four system parameters of the CHES-FY system were selected, including space distance between a pair of jaws, space distance between Bi-U-shaped pins, vertical distance between a pair of jaws and Bi-U-shaped pins, and diameter of Bi-U-shaped pins. In order to both determine the sequence of significant influences of the four system parameters on bending property, and to determine the optimal values of the four parameters to measure bending property of fabric, the Orthogonal design method was adopted to set the four system parameters as four factors and to assign four levels to each factor. Correlations were conducted between bending property and the featured indices (slope and peak value) from the pulling-out force and displacement curves recorded by the CHES-FY system. Comparing results show that the featured indices have good relations with both bending rigidity and bending length measured by FAST-2 meter as well as drape coefficient. Range values and average values are used to assess the significant relation of both factors and factor’s levels with bending property of fabric. The sequence of significant influences of the four system parameters on bending property are diameter of Bi-U-shaped pins, space distance between Bi-U-shaped pins, vertical distance between a pair of jaws and Bi-U-shaped pins, and space distance between a pair of jaws. Moreover, the optimal parameters’ levels are also obtained to better measure bending property of fabric. It indicates that the optimal system parameters of the CHES-FY system are a highly effective combination in evaluating bending property of fabric.     

Effects of structure design on resilience and acoustic absorption properties of porous flexible-foam based perforated composites

In this paper, perforated composite panel was combined with porous and resonance structures to investigate the influence on acoustic absorption and resilient properties. The perforated composite panel was fabricated based on highdensity flexible-foam via perforating and reinforcing with laminated hybrid nonwoven fabric. Effect of aperture size (AS) (ranging from 3 mm to 6 mm), perforation ratio (PR) (5 %, 10 %, 15 % and 20 %) and perforation depth (PD) (25 %, 50 %, 75 % and 100 %) on the compressive hardness, rebound resilience and acoustic absorption properties was explored. Multiply hybrid nonwoven fabric which was fabricated with low-melting point polyester (LMPET), flame-retardant polyester (FRPET) and recycled Kevlar fibers was utilized to reinforce the flexible composites and improve the acoustic property. Nonwoven that was fabricated with entangled LMPET fibers had porous structures which could reinforce the flexible foam and enhance the acoustic absorption properties. The result revealed that the continuity and supporting of porous flexible foam had directly influence the compressive hardness. The maximum hardness of the flexible-foam based perforated composites reached 420 N. The rebound resilience result showed that the sample had high resilient structure and the resilience was up to 48 %. The perforated flexible composites plate (PFP) with 4 mm-AS performed the highest acoustic absorption coefficient at 0.9. The acoustic absorption coefficient was higher than 0.8 in the frequency range from 800 to 1600 Hz and 1600 to 2400 Hz when perforated composites had 4 mm-AS at 5 % and 10 % perforation ratio. With the increase in perforation ratio, absorption peak moved from 3200 Hz to 4000 Hz. Hybrid nonwoven laminated layer help to broaden the frequency range of acoustic absorption of perforated high-density flexible foam based composites panel. Acoustic absorption coefficient was higher than 0.4 when frequency ranging from 900 Hz to 4000 Hz.     

Manufacturing technique and acoustic evaluation of sandwich laminates reinforced high-resilience inter/intra-ply hybrid composites

This study focused on the fabrication and acoustic property evaluation of sandwich cover-ply-reinforced highresilience thermal-bonding nonwoven hybrid composites. P-phenyleneterephthalamides and bicomponent high-resilience bonding polyester intra-ply hybrid nonwoven fabrics were compounded with glass plain fabric to produce the high strength sandwich structural cover ply by means of needle punching and thermal bonding to reinforce the whole composites and dissipate energy when being impacted. Then, the acoustic absorption properties of the homogenous intra-ply hybrid meshwork layer were investigated before and after being reinforced with the aforementioned cover ply. The influencing factors, including areal density, fiber blending ratio, needle punching depth, and air cavity thickness between back plate of the impedance tube and composites, were comparatively investigated. Results revealed that hybrid composites exhibited exceedingly high acoustic absorption properties. Acoustic absorption coefficients were promoted with increases in areal densities and fiber blending ratio of 3D crimped hollow polyester, particularly at low-mid frequency range. In addition, needle punching depths and back air cavity thicknesses considerably affected the average absorption coefficients. The meshwork center layer reinforced with sandwich structural cover-ply perform high resilience properties.     

Surface pretreatment of polyester fabric for ink jet printing with radio frequency O2 plasma

Plasma treatment of textiles is becoming more and more popular as a surface modification technique. It not only changes the outermost layer of a material without interfering with the bulk properties but also offers the advantage of greater chemical flexibility to obtain multifunctional textiles. Inkjet printing is becoming increasingly important and popular for the printing of textiles. When polyester fabric is inkjet printed with pigment-based inks, the printed patterns have poor color yield and easily bleeding. As a result, the fabric requires pretreatment prior to the stage of ink-jet printing. In the present study the polyester fabric was printed with magenta pigment ink after radio frequency O₂ plasma surface-treatment. At such condition, polyester fabric could obtain the effects of features with enhanced color yield and excellent pattern sharpness. The results showed that there were better patterns when the polyester fabric was treated for 9 min at a working pressure of 40 Pa and a working power 80 W. SEM images indicated that radio frequency oxygen plasma induced modifications to the surface of polyester fabric with more micro pits. Water absorption time measurement showed that the hydrophilicity of polyester fabric was remarkably improved after treatment. Anti-bleeding performance of the fabric was improved greatly, too. Therefore, radio frequency O₂ plasma treatment with the ink-jet printing technique could improve the final printed properties of polyester fabric.     

Development of Multilayered Nanocomposites for Applications in Personal Protection

The aim of the presented research was to study the influence of surface layer material on improvement of impact, dielectric, EMI shielding and sound absorption properties of sandwich composites. The sandwich composite structure consisted of Kevlar or Carbon woven fabric at the surface layer, recycled high loft nonwoven in the center and a mixture of carbon particles/epoxy matrix as a binder to hold the surface layer and core together. The carbon particles were incorporated in epoxy in order to improve failure mechanism and enhance dielectric properties or electromagnetic shielding of sandwich composites. The biggest improvements on impact properties of sandwich composites were obtained when Kevlar fabric was used as surface layer. However, surface layer of carbon fabric was found to provide better dielectric properties and improve EMI shielding of sandwich composites against Kevlar fabric surface layer.     

Investigation and modeling of air permeability of Cotton/Polyester blended double layer interlock knitted fabrics

The aim of this study was to analyze and model the effect of knitting parameters on the air permeability of Cotton/Polyester double layer interlock knitted fabrics. Fabric samples of areal densities ranging from 315–488 g/m² were knitted using yarns of three different cotton/polyester blends, each of two different linear densities by systematically varying knitting loop lengths for achieving different cover factors. It was found that by changing the polyester content in the inner and outer fabric layer from 52 to 65 % in the double layer knitted fabric did not have statistically significant effect on the fabric air permeability. Air permeability sharply increased with increase in knitting loop length owing to decrease in fabric areal density. Decrease in yarn linear density (tex) resulted in increase in air permeability due to decrease in areal density as well as the fabric thickness. It was concluded that response surface regression modeling could adequately model the effect of knitting parameters on the double layer knitted fabric air permeability. The model was validated by unseen data set and it was found that the actual and predicted values were in good agreement with each other with less than 10 % absolute error. Sensitivity analysis was also performed to find out the relative contribution of each input parameter on the air permeability of the double layer interlock knitted fabrics.     

Phenotypic Analyses of Multi-Environment Data for Two Diverse Tetraploid Potato Collections: Comparing an Academic Panel with an Industrial Panel

Phenotypic analyses of two different association panels of tetraploid potato cultivars are presented. Association panels are sets of variously related genotypes assembled for association analysis purposes. The aims of this research were to inspect, analyse and compare two phenotypic data sets, a first step in association mapping analysis. A first panel of 205 contemporary and historical cultivars, selected to represent the commercial potato germplasm pool, was evaluated in two trials in 2006, one on sandy soil and the other on clay soil, both with two replications. It was called the academic panel. Data for the second panel with 299 genotypes were compiled from contributions from five breeding companies and included 66 locations and 18 years. Each of the participating breeding companies contributed data from their clonal selection programmes for 38 advanced breeding clones and a series of standard cultivars. It was called the industrial panel. Variance components for genotypic main effects and genotype-by-environment interactions were calculated, and estimates for the random genotypic main effects were produced. The genotypic main effects for 19 agro-morphological and quality traits were used to study trait by trait correlations within each panel. In addition, for the genotypes shared by both panels, the correlation of genetic main effects between the panels was investigated. The heritability of all traits was high and no large differences were observed between panels. Coefficients of trait variation were highly correlated (r = 0.9) for both panels and trait by trait correlations in both panels showed highly similar patterns. These results demonstrate that a single-year balanced field trial as well as using breeders’ records yields robust phenotypic information that can be used in a genome-wide association study. Issues related to data management and definition of traits are discussed.     

Sound absorption and viscoelastic property of acoustical automotive nonwovens and their plasma treatment

Sound absorption property, viscoelastic property and the effect of plasma treatment of four automotive nonwoven fabrics on these properties are discussed in this research paper. Needle-punched fabrics used for vehicle headliner include 2 polyester fabrics made of hollow polyester fibers or solid polyester fibers, and 2 polypropylene-composite cellulose fabrics made of jute fibers or kenaf fibers, manufactured with the same web structure of apparent fabric density and fabric thickness. Hollow polyester fiber fabric has the highest sound absorption and the highest loss factor, the second highest is jute fiber fabric. The viscoelastic property is found to be related to the sound absorption property of fabric. The plasma treatment on nonwoven fabrics changes their sound absorption and viscoelastic property as well as their fabric weight and pore size. Hollow polyester fabric shows the increased sound absorption and viscoelastic property after the treatment with the increased pore sizes, while regular polyester fabric displays insignificant changes. The cellulose fabrics are more affected by plasma treatment compared to the polyester fabrics in terms of fabric weight loss and pore size, and jute fabric is more affected than kenaf fabric due to fiber weakness. The jute fabric demonstrates the decreased sound absorption and viscoelastic property, while kenaf fabric shows the increased sound absorption with the unchanged viscoelastic property after the treatment.     

Effect of polyester fabric through electroless Ni-P plating

Process for electroless nickel-phosphorous (Ni-P) plating has been investigated as a metallizing treatment technology on polyester fabric. The microstructure and mechanical performance of Ni-P-plated polyester fabric are investigated in this study. Surface modifications of Ni-P-plated polyester fiber were studied by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The changes in weight and thickness of the Ni-P-plated polyester fabric were determined through direct measurements. Systematic investigations, including bending rigidity, tearing strength, tensile strength, elongation at break, air permeability, wettability and absorbency, and anti-static property were conducted on untreated and metallized polyester fabrics. A thorough discussion and quantitative report were made on the specific performance of the Ni-P-plated polyester fabric.     

Transverse impact characterization of carbon woven fabric-foam sandwich composites with carbon nanotubes

Different contents of carbon nanotubes were incorporated in an epoxy matrix that was then reinforced with carbon woven fabric and foam to manufacture the carbon woven fabric-foam sandwich composites. The transverse impact characterizations of the sandwich composites were reported. The split Hopkinson pressure bar apparatus were employed to test the transverse impact behaviors. The impact wave signals were recorded and the impact load versus displacement curves and impact damages of the sandwich composites were observed to analyze the energy absorption and the impact damage mechanisms. It was found that the failure area and energy absorption is increased as the increase of impact velocity and decrease of carbon nanotubes content. The main failure modes are foam breakage and the interface delamination between the woven fabric and foam.     

Production and performance analysis of an antibacterial foot sweat pad

An antibacterial foot sweat pad was designed and produced by using materials of standard disposable absorbent hygienic products. Topsheet layer of the pad was modified by two volatile oils; cinnamaldehyde and geraniol and a standard zinc-based synthetic antibacterial agent. Physical properties of the sweat pad was arranged according to the sweat disposal amount and dimensions of a foot. Besides antibacterial performance of the topsheet layer of the pad, surface characteristics (friction test), bending rigidity of the modified topsheet layer, liquid absorption and transfer characteristics of the pad were also investigated. Subjective forearm test was conducted to determine effects of antibacterial coating materials on coolness and dampness to touch sensations created by the pads in dry and wet forms. According to the results, cinnamaldehyde created maximum antibacterial activity, which is better than the commonly used synthetic agent, on topsheet layer of the pads and geraniol had an acceptable performance. But cinnamaldehyde treated topsheet fabric became stiffer, rougher and its liquid absorption characteristics deteriorated significantly. Zinc-based synthetic antibacterial agent created higher coolness and dampness sensations during skin contact according to forearm test results.     

Experimental study on compressive,flexural and fatigue behavior of warp-knitted spacer fabrics reinforced polyurethane cast elastomer composites

This paper reports an experimental study on compressive, flexural and fatigue behavior of polyurethane cast elastomers (PCE) reinforced with warp-knitted spacer fabrics (WKSF). It aims to investigate new applications for these fabrics as the reinforcements for elastomeric parts such as shoe soles, rubber floor coverings, vibration dampening and shock absorbing pads, etc. A series of polyester WKSF with different thickness, structure of outer layer fabric and spacer yarns density was prepared and converted to PCE reinforced WKSF using the hand molding method. All the samples, including the neat PCE, were subjected to static compression, flat and spherical compression, three-point bending and flexural fatigue tests. The results showed that reinforcing PCE with WKSF, considerably enhances its spherical compressive strength (concentrated loading), flexural strength and fatigue resistance. However, it deteriorates flat compressive strength (distributed loading) and recovery behavior after static compression loading. The effect of fiber weight fraction, thickness, structure of outer layer fabric and spacer yarns density on the mentioned properties of the composites was discussed in the paper.     

Photo-thermal conversion and thermal insulation properties of ZrC coated polyester fabric

Zirconium carbide (ZrC) films are deposited onto polyester fabric through magnetron sputtering. The deposited films are then examined by using field scanning electron microscopy and energy dispersive X-ray spectroscopy. The photothermal conversion property, film thickness, infrared reflectance and transmittance, and thermal conductivity are also evaluated. The results show that the highest far-infrared emissivity of polyester fabric deposited with ZrC is 0.9379. The ZrC deposited samples showed a small increase in thermal conductivity with a difference of 0.0611W/m·K, and a higher photothermal conversion efficiency with a temperature increase of 27.5 °C in 100 s, when the thickness of the ZrC film is 1920 nm. These therefore indicate that coating fabrics with ZrC through magnetron sputtering is an environmentally friendly means to produce textiles with photo-thermal conversion and heat insulation properties.     

Mathematical simulation and experimental measurement of clothing surface temperature under different sized air gaps

The influence of air gap thickness on clothing surface temperature is analyzed by means of experimental and simulated methods. A three-dimensional body scanner is used to determine the air gap distribution between different-sized garments. The clothing surface temperature is measured by an infrared thermal camera to evaluate the heat transfer through air gap layer. The combination of two non-contact measuring techniques is a novel way to investigate the relationship between air gap thickness and clothing surface temperature. A mathematical model is set up to simulate the heat and moisture transfer from skin to environment by including the sensible and latent heat transfer through air gap layer under clothing, fabric layer and boundary air layer adjacent to the fabric. The established mathematical model is used to forecast the surface temperature and evaluate the heat transfer capacity of different sized garments.