Reinforcement Yarns Research Articles

Simulation of the tensile behaviour of biaxial knitted fabrics produced based on rib structure using a macro constitutive model

This study presents a macro-scale constitutive model to simulate the tensile behaviour of biaxial weft knitted fabrics produced based on a 1 × 1 rib structure. Fabrics were produced using polyester yarns as stitch yarns and nylon yarns as straight yarns in a modern flat knitting machine. Stress–strain curves of 1 × 1 rib structure and corresponding biaxial knitted fabric were measured in three different directions (course, wale and 45 degrees) on a tensile tester. Based on extracted results, a constitutive equation was proposed for macro modelling of biaxial knitted fabrics. The stiffness matrix of the biaxial knitted fabrics was assumed to be a combination of the stiffness matrix of 1 × 1 rib and reinforcement yarns. A UMAT subroutine was provided to implement the constitutive behaviour in Abaqus software. To evaluate the accuracy of the proposed model, fabric tensile behaviour in 22.5° and 67.5° directions were simulated and compared with experimental results. The results showed that the macro model can successfully predict the tensile behaviour of the biaxial weft knitted fabric in different directions.

Strain sensing of structural composites by integrated piezoresistive CNT yarn sensors

This work presents the development of piezoresistive strain sensors for the next-generation airframe parts. The sensors consist of polyetherketoneketone (PEKK) coated thermoplastic filaments with a continuous carbon nano-tube (CNT) yarn reinforcement fully integrated into the structural thermoplastic CFRP laminates. PEKK coating improves the piezoresistive behaviour of CNT yarns by increasing internal stress transfer. When consolidated in a laminate, the CNT sensors have a gauge factor of 10.5 and 12 for 0.2 % tensile and compressive deformations, respectively. The CNT sensors were calibrated and compared with commercial strain gauges at the coupon level and demonstrated high sensitivity in three- and four-point bend tests.

Experimental study on the quality of drilled holes in Sabai grass reinforced composites

Hole quality in composites plays very important role in the production of close tolerance holes in automobile parts. Through drilling experiments in Sabai Yarn reinforced composite, this study examines the impact of different input parameters like feed rate, rpm, and tool diameter. The circularity of hole was measured with the help of CMM. The circularity error was reported in the range of 0.037 to 0.1628 mm. Design of experiments and Taguchi method have been used to study the effect of process parameters. The circularity of hole mainly depends on feed rate and rpm in the drilling process of Sabai yarn composite. The circularity error and delamination are minimum in treated reinforcement in yarn (0°) and woven yarn (0°/90°) compared to the untreated reinforcement yarn (0°) and woven yarn (0°/90°). Due to strong bound strength fibres cannot pull-out its cut with tool edge so that it gives smooth machined surface in treated reinforcement. The chip formation in drilling depends on the feed rate and tool diameter. Chips are discontinuous at the higher feed rate and higher rpm.

Optical inspection of the braid formation zone during manufacturing of preforms from reinforcement fibers for defect detection purposes

Braiding is a highly automated process for manufacturing preforms directly from reinforcement yarns at large production volumes. The quality of braided textiles and the stability of the process can however be negatively affected by defects that occur during braiding. If such defects can be detected from fine process anomalies early during their formation, the process can be interrupted and countermeasures can be introduced before the defect aggravates and gets braided into the product. Current sensor modules for defect detection during braiding however involve problems of either late response times, process impairments or a lack of applicability to braiding of composite parts. In an effort to overcome these drawbacks, the paper at hand proposes to optically monitor the braid formation zone by means of a single camera (no process impairments). An associated image analysis algorithm creates a measure for the angular distance of each individual braiding yarn to its neighboring yarns and tracks the yarns as they rotate around the overbraidable mandrel (typical for braiding of composite parts). Since braiding yarns typically exhibit distinct curvatures as they span from the bobbins towards the center of the braiding machine due to frictional yarn-yarn interaction, a change in yarn curvature and thus in angular yarn distance is an early sign of a defect-characteristic anomaly in yarn tension (early response). If implemented on a real-time capable computing device, an apparatus according to the presented method can be retrofitted to existing production lines for braiding process monitoring. It then contributes to the reduction of error correction times since countermeasures are quicker to implement as long as the defect has not aggravated, yet. Furthermore, scrap material rates can be reduced as anomalies can be detected before they manifest in the braided structure.

Compression properties of unidirectional over-braided multilayer composites

A unidirectional (UD) braided structure was developed to improve the in-plane mechanical performance of the two-dimensional (2D) braided composites. The basic compression properties of UD braided composites need to be studied to broaden their application. In UD over-braided multilayer composites (UDMLCs), the braid angle gradually increases from the first layer to the last one. This work found that a slight range variation (2°–5°) in the mean braid angle (calculated by averaging the braid angles of all layers) of UDMLCs had a significant effect on the compression modulus and little effect on the compression strength. The reinforcement (braided) yarn off-axis orientation introduced shear under compression load. The gradual increase of the braid angle from the first to the last layer created a load gradient in the thickness direction. These helped to reveal the formation mechanism of the kink band which was the key reason leading to catastrophic compression failure. Compared with 2D over-braided multilayer composites (2DMLCs), the compression modulus and strength of UDMLCs increased by 9.08% and 15.84%, respectively. However, the interweaving of reinforcement yarns and the nesting between layers in 2DMLCs made their integrity better than that of UDMLCs. Meanwhile, the interwoven structure of 2DMLCs also made their structural stability better than that of UDMLCs.

Experiments and calibration of a bond-slip relation and efficiency factors for textile reinforcement in concrete

Textile reinforcement yarns consist of many filaments, which can slip relative each other. At modelling of the global structural behaviour, interfilament slip in the yarns, and slip between the yarns and the concrete can be considered by efficiency factors for the stiffness and strength of the yarns, and by applying a bond-slip relation between yarns and concrete. In this work, an effective and robust method for calibration of such models was developed. Two-sided asymmetrical pull-out tests were carried out, with varying embedment lengths designed to obtain both pull-out and rupture of the textile as failure mode. The efficiency factors for strength and stiffness of the textile were very similar, 34% and 35% respectively. This indicates the stress distribution within a yarn to be uneven in a similar manner for small and large stress levels, and that interfilament slip has a larger influence than variation of filaments’ strength.

Performance of Sustainable Flax Yarn Reinforced Polyester Laminate “Exploratory Study”

Performance of Sustainable Flax Yarn Reinforced Polyester Laminate “Exploratory Study”

Non-woven textiles for medical implants: mechanical performances improvement.

Non-woven textile has been largely used as medical implant material over the last decades, especially for scaffold manufacturing purpose. This material presents a large surface area-to-volume ratio, which promotes adequate interaction with biological tissues. However, its strength is limited due to the lack of cohesion between the fibers. The goal of the present work was to investigate if a non-woven substrate can be reinforced by embroidery stitching towards strength increase. Non-woven samples were produced from both melt-blowing and electro-spinning techniques, reinforced with a stitching yarn and tested regarding several performances: ultimate tensile strength, burst strength and strength loss after fatigue stress. Several stitching parameters were considered: distance between stitches, number of stitch lines (1, 2 or 3) and line geometry (horizontal H, vertical L, cross X). The performance values obtained after reinforcement were compared with values obtained for control samples. Results bring out that reinforcement can increase the strength by up to 50% for a melt-blown mat and by up to 100% for an electro-spun mat with an X reinforcement pattern. However, after cyclic loading, the reinforcement yarn tends to degrade the ES mat in particular. Moreover, increasing the number of stitches tends to fragilize the mats.

Engineering the geometry of novel yarns for flexible, hybrid composites Part I: Multiple breaks

This study reports on the development of a novel form of yarn reinforcement for making super tough, flexible composites. The concept is based on the rupturing of components of the composite yarn many times before totally breaking. The composite yarn structure has a configuration of three main components − helical, straight and sinusoidal. The components are not restricted by the type of raw material, and any type of fibre or blend can be used. Experimentally, the hollow-spindle spinning system was used to make nine variants of this composite yarn. These variants were tested for their tensile behaviour at an extension rate of 250 mm/min. It was found that the core component of two of the nine variants had eight breakages, while the core component of the remaining variants had four to five breakages before the final break of the core component. The main mechanism that allows the core component yarn to break so many times is a locking applied to it by the wrapping yarn during stretching. The gain in strength for these variants was 21–81% in comparison with a typical twistless composite yarn. Flexible composites made of such yarn configurations can find numerous uses in construction, geotextiles, ballistic protective garments, aerospace, automotive and shipping industries.

Development and mechanical properties of three-dimensional flat-knitted fabrics with reinforcement yarns

Three-dimensional (3D) flat-knitted fabrics have become a topic of interest in the field of composites in recent years because of the growing need for rapid preparation of complicated shape preforms. In order to improve the mechanical properties of 3D flat-knitted fabrics, two types of 3D flat-knitted fabrics with reinforcement yarn (FKFR) were developed using ultra-high molecular weight polyethylene (UHMWPE) yarn. Their basic structures were composed of plain structure and interlock structure with tuck stitch, respectively, and the reinforcement yarn was integrated into the fabric as the weft inlay. The tensile, bending, drape, and bursting properties of the two fabrics were characterized. Results showed that the basic structure of the fabric has impacted on the mechanical properties of the fabric significantly. The tensile and bending properties of the fabric with interlock structure were better than that of the fabric with plain structure. During the transverse stretching process, the surface structure of the fabric with interlock structure was more stable. Moreover, transverse yarn strength utilization of the fabric with interlock structure was 1.05, which reached the level of ordinary woven fabric. In addition, the bursting force of the fabric with excellent tensile properties was lower than that of the fabric with a plain structure because the latter has better extensibility.

A Comparative Study of the Mechanical Properties of Jute Fiber and Yarn Reinforced Concrete Composites

ABSTRACTA relatively better performance of jute fiber and yarn reinforced concrete composites can open up a wide access to application of natural resources in concrete strengthening. In order to achieve this goal, an experimental investigation on the flexural, compressive and tensile strengths of Jute Fiber Reinforced Concrete Composites (JFRCC) and Jute Yarn Reinforced Concrete Composites (JYRCC) has been conducted. To draw a specific conclusion, the mix ratios of 1:1.5:3 and 1:2:4 (by volume) of concrete have been maintained with incorporation of jute fiber and yarn in concrete mortar having different cut lengths with distinct volumetric ratios. Finally, a comparison of the JFRCC and JYRCC strength increments with respect to the plain concrete has been investigated. A significant increment of compressive, flexural and tensile strength was observed only for a short cut length having a low volumetric ratio, where JYRCC increment value was always found progressive. A far more regular arrangement and adequate mixture of JYRCC was also visualized compare to JFRCC in concrete mortar. All the principal increment values were found only in case of JYRCC with a mix ratio of 1:1.5:3. So, it can be concluded that the presence of jute yarn and more cement content can strengthen the concrete to a great extent.

Shear strength of interfaces between unsaturated soils and composite geotextile with polyester yarn reinforcement

Composite geotextiles with polyester yarn reinforcement have been commonly used in combination with unsaturated soils. Both unsaturated and saturated shear strength of the interfaces were investigated between a composite geotextile and three major types of materials: silty sand (SM), low-plasticity silt (ML) and high-plasticity clay (CH) in a direct shear box. The interfaces were formed using two methods (A and B) to reflect the wide range of possible contact conditions in practice. Method A involved statically compacting the soil directly on top of the composite geotextile, while for Method B, the soil was statically compacted in a separate mold and later brought into contact with the composite geotextile. Type B interfaces required a larger displacement to mobilize the shear strength than Type A interfaces. The ultimate failure envelopes of SM and ML soils were similar to those of their interface shearing. Notably, the failure envelopes for the clay-geotextile interface of both types were higher than that of clay alone. The unsaturated soil-only shearing had a higher peak strength and tended to dilate more than saturated soil-only shearing, while unsaturated soil-interface shearing appeared to be more contractant than saturated interface shearing. The strength variations with suction for all tested soils and interface shearing were clearly non-linear. A new model that takes account of the condition of soil-geotextile contact intimacy is proposed for predicting the variation of interface strength with suction, based on the variation of the soil's apparent cohesion with suction and the geotextile-water retention curve.

Textile technologies for the manufacture of three-dimensional textile preforms

Purpose This paper aims to provide an overview of the current manufacturing methods for three-dimensional textile preforms while providing experimental data on the emerging techniques of combining yarn interlocking with yarn interlooping. Design/methodology/approach The paper describes the key textile technologies used for composite manufacture: braiding, weaving and knitting. The various textile preforming methods are suited to different applications; their capabilities and end performance characteristics are analysed. Findings Such preforms are used in composites in a wide range of industries, from aerospace to medical and automotive to civil engineering. The paper highlights how the use of knitting technology for preform manufacture has gained wider acceptance due to its flexibility in design and shaping capabilities. The tensile properties of glass fibre knit structures containing inlay yarns interlocked between knitted loops are given, highlighting the importance of reinforcement yarns. Originality/value The future trends of reinforcement yarns in knitted structures for improved tensile properties are discussed, with initial experimental data.

Electrospun Yarn Reinforced NanoHA Composite Matrix as a Potential Bone Substitute for Enhanced Regeneration of Segmental Defects.

Nanohydroxyapatite (nanoHA) is a well-established synthetic bone substitute with excellent osteoconduction and osteointegration. However, brittleness coupled with slow degradation curtails its load-bearing and bone regeneration potential, respectively. To address these limitations, nanoHA composite matrix reinforced with electrospun fibrous yarns was fabricated and tested in vitro and in vivo. Different weight percentages (5, 10, 15 wt%) and varying lengths (short and continuous) of poly(l-lactic acid) yarns were randomly dispersed in a gelatinous matrix containing nanoHA. This significantly improved the compressive strength as well as work of fracture, especially for continuous yarns at high weight percentages (10 and 15 wt%). Incorporation of yarns did not adversely affect the pore size (50-350 μm) or porosity of the scaffolds as well as the in vitro cellular response. Finally, when tested in a critical-sized femoral segmental defect in rat, the nanocomposite scaffolds induced osteoblast cell infiltration at 2 months that subsequently underwent increased mature lamellar bone formation at 4 months, in both the mid and peripheral defect regions. Histomorphometric analysis demonstrated that new bone formation and biomaterial degradation were significantly enhanced in the composite scaffold when compared to commercially available HA. Overall, the composite matrix reinforced with electrospun yarns proved to be a potential bone substitute having an appropriate balance between mechanical strength, porosity, biodegradation, and bone regeneration ability.

Microscale finite element model of brittle multifilament yarn failure behavior

A microscale model of multifilament reinforcement yarns made of technical carbon fibers is established based on the finite element method. The model is used to perform simulations of tensile failure. The failure behavior of dry multifilament carbon yarns is modeled using a maximum stress criterion with statistical distribution of the strength. The maximum stress is assigned to every single element and varied according to a normal distribution found in experimental tests of single filaments. The Weibull distribution is used for calculating the local failure stress. The material parameters are calculated in function of the element size to account for the volume-specific statistical breaking effect. Representative simulations of the tensile failure behavior prove the concept of the introduced assumptions.

Simulation of the spherical deformation of biaxial weft-knitted fabrics using meso and macro models

The main objective of this research is the numerical simulation of the spherical deformation of biaxial weft-knitted fabrics produced based on 1×1 rib structure. Biaxial knitted samples were produced on a modern flat knitting machine using the polyester yarn as the fabrics stitch background and the nylon yarn as the reinforcing inlays. Bagging test was applied to the samples for investigating their behaviors during the spherical deformation. Considering two different approaches in analytical studies, the test procedure and its results were simulated through the Abaqus software environment based on the finite element method. In the first approach, by the help of Python scripting, the real structure of the fabric was simulated based on a unit-cell of the three-dimensional loop model for 1×1 rib structure comprised of warp and weft reinforcing yarns. In the second approach a constitutive equation was used for macro modeling of biaxial knitted fabrics. The stiffness matrices of these fabrics were assumed to be a combination of stiffness matrices for both 1×1 rib based-structure and reinforcement yarns. To implement the constitutive behavior in Abaqus software, a VUMAT subroutine was provided. To evaluate the accuracy of the two suggested models, fabric spherical deformation was simulated and results were compared with experimental measurements. The findings showed that the both models can successfully predict the spherical deformation of the biaxial weft knitted fabric.

Development of multiaxial warp knitting technology for production of three-dimensional near net shape shell preforms

The possibility of direct preforming in the near net shape of final component structure with load- and shape-conforming fiber orientations is highly essential in composite production, not only to reduce costs but also to attain better mechanical properties and form stability. Based on the concept of varying the reinforcement yarn lengths during the feed-in (warp yarn delivery) and segmented doffing, synchronous working numerically controlled warp yarn delivery and doffing machine modules have been newly developed for multiaxial warp knitting machines to create a resource efficient textile process chain by a single-step, large-scale oriented production of load- and form-conforming warp knitted three-dimensional shell preforms with free-form geometrical surfaces. Such customized preforms in the near component net shape offer higher material utilization and increased lightweight potential.

3-D printing of multifunctional carbon nanotube yarn reinforced components

Continuous carbon nanotube (CNT) yarn filaments can be employed as an inherently multifunctional feedstock for additive manufacturing (AM). With this material, it becomes possible to use a single material to impart multiple functionalities in components and take advantage of the tailorability offered by fused filament fabrication (FFF) over conventional fabrication techniques. Some of the challenges associated with coupling this emerging material with advanced processing are addressed here through the fabrication and characterization of additively manufactured functional objects. Continuous CNT yarn reinforced Ultem® specimens are characterized to determine their mechanical and electrical properties. The potential to produce net shape fabricated multifunctional components is demonstrated by additively manufacturing a quadcopter frame using Ultem® and continuous CNT yarn reinforced Ultem®, where the CNT yarn reinforcement was designed to also act as the electrical conductors carrying current to the motors.

Engineering Fiber Volume Fraction of Natural Fiber Staple - Spun Yarn Reinforced Composite

There is a large demand for high fiber volume fraction natural fiber reinforcement polymer composites. Among many parameters affecting the mechanical properties of a composite, the fiber volume fraction is the most decisive factor. The effect of fiber volume fraction on the physical and tensile properties of aligned natural fiber staple spun yarn composites has been intensively investigated. However, there have been no direct studies on determining the relation between composite fiber volume fraction and the yarn fiber volume fraction for fiber staple-spun yarn composite. With the intention to improve the utilization of most fibers of the yarn cross section in the composite, the variation of the yarn diameter in staple-spun yarn reinforced composite is investigated in this study. The analysis of the yarn diameter indicates that it has a high variability that necessitates an increase in the composite diameter to envelope all the yarn body leading to reduction in its fiber volume fraction. A model for the determination of composite fiber volume fraction was driven, grounded on the analysis of the yarn diameter variability along its length. An equation has also been developed to calculate the diameter of the composite to cover majority of yarn cross section

Effect of jute yarn on the mechanical behavior of concrete composites.

The objective of the study is to investigate the effect of introducing jute yarn on the mechanical properties of concrete. Jute fibre is produced abundantly in Bangladesh and hence, very cheap. The investigation on the enhancement of mechanical properties of concrete with jute yarn as reinforcement, if enhanced, will not only explore a way to improve the properties of concrete, it will also explore the use of jute and restrict the utilization of polymer which is environmentally detrimental. To accomplish the objective, an experimental investigation of the compressive, flexural and tensile strengths of Jute Yarn Reinforced Concrete composites (JYRCC) has been conducted. Cylinders, prisms and cubes of standard dimensions have been made to introducing jute yarn varying the mix ratio of the ingredients in concrete, water cement ratio, length and volume of yarn to know the effect of parameters as mentioned. Compressive, flexural and tensile strength tests had been conducted on the prepared samples by appropriate testing apparatus following Standards of tests. Mechanical properties of JYRCC were observed to be enhanced for a particular range of lengths of cut (10, 15, 20 and 25 mm) and volume content of jute yarn (0.1, 0.25, 0.5 and 0.75 %). The maximum increment of compressive, flexural and tensile strengths observed in the investigation are 33, 23 and 38 %, respectively with respect to concrete without jute yarn.