Yarn Cross-section Research Articles

Microscopic Investigation of Quartz Fiber Fabrics: Geometry Model

In response to the relationship between perform structural parameters and the composites properties, a newly geometrical modeling of 2D biaxial orthogonal woven fabric was established in this paper. Based on the yarn’s true configuration, the SEM image of the yarn cross-section was taken, geometrical parameters (the individual tow geometry and weaving pattern of the fabrics) are introduced in order to describe the general families of woven fabrics. The tow waviness can be described by combinations between undulated and straight segments and the tow cross-section can be described by lenticular shape. When the geometrical model was used to predict the structural properties of the fabric, the predicted values show good agreement with the measured ones. The geometrical model proposed here is intended as the foundation for further design and analytical of the mechanical properties of the composite materials reinforced with these fabrics.

Study of mechanical behavior of Kevlar/polypropylene hybrid yarns and their composites

Abstract In this paper, the mechanical characteristics of Kevlar multi-filament-polypropylene (KV M/F-PP) hybrid yarns and its composites have been studied. The hybrid yarns have been prepared by the principle of friction spun method in a DREF-3 (Dr Ernst Fehrer A.G. the name of the inventor 1973) Machine. The system uses Kevlar-29 (poly paraphenylene terephthalamide) multifilament (KV M/F) and polypropylene (PP) of 38 mm staple length fibres as core and sheath materials, respectively. The tensile properties of selected reinforcing materials and hybrid yarns are tested before preparing the composite samples. The weight percentages of KV M/F were kept as 0%, 15%, 20%, 25% and 30% corresponding to the percentages of matrix. DREF-3 hybrid yarns are characterized by very homogeneous component distributed over the yarn cross-section. The hybrid yarn is used for thermoplastic composites in compression molding, where Kevlar multifilaments take place in core as reinforcing materials and sheath or wrapped PP fibres as matrix. The prepared composite samples have been studied using specific standards to evaluate the void volume fraction and the tensile behavior in the standard conditions. The composite having 30% of Kevlar shows the highest tensile strength with a high void percentage, however, the elongation to break is a minimum due to lower weight percentage of low elastic modulus polypropylene matrix as compare to other samples.

An Image Analysis Method for Studing Yarn Cross-Sectional Structure

In this paper, we propose an analysis method for examining yarn cross-sectional structure. After obtaing yarn cross section photos, annular equal area yarn model and binary operation were used for image analysis and treatment. Then, statistic method was applied to analyze the distribution of fiber area in equal areas. The centroid position of the fiber and yarn were calculated, and the percentage values of the fiber area in each equal division against its circle (ring) area were obtained by using an ImageJ software. Finally a yarn sample was examined, and results show that this method is useful.

Modelling of yarn flattening in woven fabrics

The main aim of the study is to investigate how the yarn cross-section changes along the yarn path in woven fabrics and how these changes relate to the yarn and fabric parameters such as yarn linear density, twist factor, warp and weft cover factors. Based on the elliptical cross-section model, yarn flattening coefficients were calculated along the yarn path. A general equation of change in yarn flattening coefficient was developed in the form of e = a1 + a2cosN(x) and the equation coefficients were analysed to find out the effects of the control factors. Twist factor was found to be the primary factor that had effects on a1 and a2, whereas the yarn linear density caused the highest change in N value.

Surface activation of dyed fabric for cellulase treatment

Surface activation of fabric made from cellulose fibres, such as viscose, lyocell, modal fibres and cotton, can be achieved by printing of a concentrated NaOH-containing paste. From the concentration of reducing sugars formed in solution, an increase in intensity of the cellulase hydrolysis by a factor of six to eight was observed, which was mainly concentrated at the activated parts of the fabric surface. This method of local activation is of particular interest for modification of materials that have been dyed with special processes to attain an uneven distribution of dyestuff within the yarn cross-section, e.g., indigo ring-dyed denim yarn for jeans production. Fabrics made from regenerated cellulose fibres were used as model substrate to express the effects of surface activation on indigo-dyed material. Wash-down experiments on indigo-dyed denim demonstrated significant colour removal from the activated surface at low overall weight loss of 4-5%. The method is of relevance for a more eco-friendly processing of jeans in the garment industry.

A Numerical Simulation on Ballistic Penetration Damage of 3D Orthogonal Woven Fabric at Microstructure Level

The ballistic impact damages of 3D orthogonal woven fabric (3DOWF) penetrated under a conically cylindrical rigid projectile were investigated from experimental tests and finite element simulations. A microstructure model of the 3DOWF was established and imported into finite element geometrical preprocessor. In the microstructure model, the architecture of the 3DOWF has the same spatial configurations with that of the real 3DOWF, including the spatial distributions and cross-sections of warp, weft yarns, and Z-yarns. Mechanical parameters of the yarns were obtained from high-strain rate tests which near to the impact loading condition in ballistic tests. The impact damage evolutions of the 3DOWF were simulated with the commercial finite element code ABAQUS/Explicit. From the comparisons of damage morphologies and residual velocities of the projectile after perforation between experimental and finite element simulation, it was found that the simulation can reflect the impact damage precisely. Furthermore, the stress wave propagation and damage mechanisms can be revealed from the microstructure model. Insights gained from this study will prove extremely useful in further material and architectural studies that will ultimately lead to optimization of the 3DOWF structure.

An application of queuing theory to modelling of melange yarns. Part II: A method of estimating the fibre migration probabilities and a yarn structure simulation algorithm

A queuing model of staple yarn structure was presented in Part I of this work, where the migration behaviours of fibres were simulated by the movement of customers in a Markovian network of queuing systems. Part II of the series proposes (i) a multi-dimensional minimization method for estimating the migration probabilities of fibres based on the analysis of the distribution of number of fibres in yarn cross-sections; (ii) a yarn structure simulation algorithm which uses the migration probabilities of fibres, yarn technical specifications (e.g. linear density and twist) and colour composition to produce a realistic three-dimensional image of a melange yarn. The result is a high quality three-dimensional image of a melange yarn showing its fibrous structure as well as the formation of hairiness. Due to the generic nature of the model and the simulation algorithm, this approach can be applied to a wide range of yarns including ring-spun or open-end spun yarns of solid shade or produced from melange blends. Further improvements to the proposed model are discussed including the application of inhomogeneous Poisson process and the analysis of energy relationships which govern the migration behaviour of fibres.

Study of the criteria for radial distribution of components in cross sections of yarn by computer modeling

Experiments were conducted on computer modeling of the cross section of two-component yarn. The sensitivity of each of the criteria of radial distribution of the fibres in the cross section of yarn made from a blend of chemical fibres was determined. The area of application of each criterion was determined with consideration of the results of the computer experiments.

The Discussion of the Yarn Cross-Section Shape of Woven Fabrics

The form character and oblate shape of cross-section of the yarn in woven fabrics are discussed. Various fabric samples are made by using 106 tex cotton yarn as warp and weft, with changing warp densities and fabric structures as plain、1/2 twill and 1/3 twill respective. The diameter d and horizontal diameter a of the yarn are measured by analyzing the images of the fabric slice. Then the stave extension width coefficient δ of yarn cross-section is calculated. The result shows that there are three different kinds of cross-section shapes of the yarn in fabric as ellipse or similar convex lens, similar to egg shape and similar to shoulder squareness. The more complex of the weave structure, the more kinds of cross-section shape of the yarn has. The yarn cross-section presents different oblate shapes along with the changing densities of interweaving in area A, area B and area C.

Yarn geometry in woven fabrics

Geometrical models of textile structures are important to the design, manufacture and performance prediction of textile related products. The models existing in the textile literature do not take into account the variable deformation of the yarn cross-section along the yarn path and this seriously limits the accuracy of these models. The main aim of our study was to investigate how the yarn cross-section shape changes along the yarn path in the woven fabrics and how these changes relate to the yarn and fabric parameters such as yarn linear density, twist factor, warp and weft cover factors. Based on the elliptical cross-section model, models that describe how major and minor radii were affected by the control factors were developed.

A novel weave pattern encoding method using neighbor information and its applications

Determination of features of weave patterns is a crucial task in practice, including determination of equivalent weave patterns, determination of weave type, repeat period detection, pattern correction, representation of fabric structures and pattern searching from a collection of weave patterns. Most previous research on the problems is based on binary matrix operations. In this paper, a simple and efficient encoding algorithm and its implementation are presented to reveal the hidden information in the binary matrix of a weave pattern and thus to find a solution to determine features of the weave pattern. By compiling the 32 components with different shapes of yarn cross-sections, it is possible to quickly produce the required weave geometries and weave textures at different levels of detail. A set of frequency matrices of a weave pattern can be considered as the fingerprint where each weave pattern is uniquely endowed with a set of frequency spectra. It therefore enables us to perform a weave pattern search in the database to locate weave geometries and weave textures. Our experiments report a satisfactory result on the problems.

High performance flame-retardant composite yarns with oxidized fiber

This study employed a SKF draft system equipped with an additional spreading device to form a high performance flame-retardant composite yarn. For mixing the spread Technora® filaments and Stretch-Broken oxidized fibers, nip of the front rollers was arranged for best dispersion. The yarn unevenness (CV %), strength, abrasion-resistance, and Limited Oxygen Index (LOI) of the composite yarn were evaluated. The cross-sections of the actual composite yarn were observed to assess its structure and the effect on yarn performance. The experimental results showed that the yarn CV% is worse as the yarn count (Tex) tend to be finer. This would be an optimum condition adopting 30 TM for the yarn evenness and yarn strength. After abrasion test, the residual strength of composite yarns remains above 80 %. The LOI value depends on the coverage degree of oxidized fiber outside the yarn surface, and there tended to be a lower LOI value with finer yarn count (Tex). Overall, the T/O composite yarn with uniform distribution structure can provide high performance and flame-retardancy.

Theoretical study on the bending rigidity of filament yarns with an elliptical cross-section using energy method. II. Numerical evaluation

This is the second part of a series of work investigating on the bending rigidity of filament yarn with an elliptical cross-section. In the present paper, the quantitative error analysis of the earlier simplification of a circular cylindrical of yarn geometry under deformation is evaluated, and the effects of filament properties on yarn bending rigidity are also evaluated. It is highly useful in preciously predicting yarn bending property from filament behaviors for virtual processing of textile materials. So the explicit formula derived in the Part I of this series for the elliptical cylindrical of yarn geometry is used to compute the quantitative error of the earlier model. The four characters, including the eccentricity of elliptical cross-section of yarn, the ratio of bending to torsional rigidity of filament, the helix angle of filament on yarn surface and the number of filaments inside the yarn, are adopted to quantify the bending rigidity relationship between the filaments and yarn. Based on the analytical method, the earlier method in which the circle shape takes place of the elliptical shape of yarn cross-section for simplification is evaluated. The simulation results show that the relative error of the circle assumption is not higher than 10 % when the eccentricity of yarn cross-section is lower than 0.8. However if the eccentricity is higher than 0.8 and the helix angle is larger than 30 degrees, it is suggested to conduct the deformation analysis based on the elliptical cross-section of yarn.

Theoretical study on the bending rigidity of filament yarns with an elliptical cross-section using energy method. I. Theoretical modeling

The geometrical model of yarn currently in use is assumed to be a circular cylindrical under the bending deformation, but this assumption is not really true because the cross-section of yarn has to change to an elliptic shape when the compressive force acted on the yarn is considered. Therefore, as the first part of a series of work, the present paper considers the fact that yarn geometry changes from a circular cylindrical to an elliptical cylindrical under an external applied bending moment, and then analyzes the relationship of bending rigidity between constituent filaments and the formed yarn, which is useful in predicting or selecting specified bending property of filaments by the requirements of yarn. In the present paper, the bending and torsional energies stored in filaments are analyzed according to their deformations by the energy method. The explicit formula is then obtained to quantify the bending rigidity relationship between the filament and yarn, in which four characters are featured as the eccentricity of elliptical cross-section of yarn, the ratio of bending to torsional rigidity of filament, the helix angle of the filament on yarn surface and the number of filaments inside the yarn. Moreover, the bending rigidity of filament yarns formulated by an earlier method with a circle shape assumption can also be obtained by the proposed method with the eccentricity being equal to zero. Based on the analytical solution, the earlier method in which the circle shape takes place of the elliptical shape of yarn for simplification can also be evaluated. This will be depicted in the Part II of this series of work, in which the relative error between the ideal and revised model would be analyzed, and the numerical simulations of relationship between filament and yarn would also be made.

Local damage in a 5-harness satin weave composite under static tension: Part I – Experimental analysis

This paper presents an experimental damage analysis of a 5-harness satin weave carbon–PPS (polyphenylene sulphide) composite under uni-axial static tensile load. In order to understand the local damage behaviour, tensile tests were performed and accompanied by acoustic emission (AE) and microscopic analysis of the composite specimen. These tests enable us to detect the damage initiation stress as well as the damage initiation location in the composite. Microscopic observation of the tested composite laminates allowed the characterization of the sequence of intra-yarn transverse damage (perpendicular to the load direction) occurrence at different locations in the laminate, starting from crack initiation to the final failure of the composite.The earliest crack events occurred inside the laminate middle layers, followed by the damage on the traction free surface. It is observed that the initiation of the transverse crack, the location of the crack in the weft yarn cross-section (centre/near the edges) is affected by the relative position of the ply in the laminate (local nesting configuration). The first part of this paper deals with the experimental characterization of sequential damage in a 5-harness satin weave composite. Part II deals with the meso-FE modeling of damage using a satin weave unit cell, and the correlation between experimental and numerical results.

Internal geometry evaluation of non-crimp 3D orthogonal woven carbon fabric composite

Measurements of the internal geometry of a carbon fiber non-crimp 3D orthogonal woven composite are presented, including: waviness of the yarns, cross sections of the yarns, dimensions of the yarn cross sections, and local fiber volume fraction. The measured waviness of warp and fill yarns are well below 0.1%, which shows that the fabric termed here “non-crimp” has nearly straight in-plane fibers as-produced, and this feature is maintained after going through all steps of fabric handling and composite manufacturing. The variability of dimensions of the yarns is in the range of 4–8% for warp and fill directions, while the variability of the yarn spacing is in the range of 3–4%. These variability parameters are lower than respective ranges of variability of the yarn waviness and the cross-sectional dimensions in typical carbon 2D weave and 3D interlock weave composites, which are also illustrated in this work for comparison.

Multiscale modeling of the impact of textile fabrics based on hybrid element analysis

In this work, a multi scale modeling approach has been developed to simulate the impact of woven fabrics using a finite element (FE) analysis. A yarn level of resolution is used in the model. This approach, referred to as the hybrid element analysis (HEA) is based on decreasing the complexity of the finite element model with distance away from the impact zone based on the multiscale nature of the fabric architecture and the physics of the impact event. Solid elements are used to discretize the yarns around the impact region, which transition to shell elements in the surrounding region. A new method for modeling the shell yarns is incorporated that more accurately represents the contours of the yarn cross section. Impedances have been matched across the solid–shell interface to prevent interfacial reflections of the longitudinal strain wave. The HEA method is validated by first applying it to the FE model of a single yarn for which an analytical solution is known. The HEA method is then applied to a woven fabric model and validated by comparing it against a baseline model consisting of yarns discretized using only solid elements.

The effect of the processing factors on the physical properties of high shrinkable nylon composite yarns

This paper is aiming to develop high shrinkable differential shrinkage and mixed fibre nylon composite yarns by applying the high shrinkable polyester manufacturing technology. The wet and dry thermal shrinkages and mechanical properties of developed nylon composite yarns are measured and discussed with processing factors in the spinning and texturing processes. And the effects of the processing factors on the physical properties of high shrinkable nylon composite yarns are investigated. For this purpose, twenty seven nylon 30d/12f SDY were prepared with variation of spinning temperature, 2nd godet roller temperature and draw ratio on the spinning machine. The optimum spinning condition which showed maximum wet thermal shrinkage and stress was determined and high shrinkable nylon 30d/12f SDY spun under this optimum condition used as a core and three kinds of regular nylon filaments used as sheath were processed on the texturing machine with variation of 1st and 2nd heater temperatures. The optimum texturing process condition was decided through analysis of dry thermal shrinkage of these core and sheath nylon filaments. Finally, high shrinkable differential shrinkage and mixed fibre nylon composite yarns were made under the optimum texturing condition on the texturing machine, its wet thermal shrinkage was 13.8 %, which was much more higher than that of regular nylon composite yarns. The differential shrinkage effect of the developed nylon composite yarns was found in the yarn surface and cross section profiles by microscope and SEM.

Studies of Flexible Fiber Trajectory and Its Pneumatic Condensing Mechanism in Compact Spinning with Lattice Apron

A dynamic model of the infinitesimal element of the flexible fiber is proposed, which describes the flexible fiber trajectory in the condensing zone of compact spinning with lattice apron. Based on the flow simulation in the condensing zone, the flexible fiber trajectory is simulated by a specially designed Matlab program routine. The trajectories of the fibers of different initial positions can explain the pneumatic condensing mechanism in the condensing zone. The results show that fiber trajectories of different initial positions in the condensing zone gradually converge, and the condensing process of the fiber bundle is divided into three parts: the rapid condensing region, the adjustive condensing region and the steady condensing region. The fibers of different initial positions will be interlaced for position change in yarn cross-section, caused by the airflow in the condensing zone. Moreover, fibers will gradually close the surface of the lattice apron when fibers are delivered from the rapid condensing region to the steady condensing region.

A New Analytical Solution of the Twist Wave Propagation Equation with its Application in a Modified Ring Spinning System

This paper is devoted to the formulation of new analytical solutions and exploration of physical interpretation for yarn twist propagation in staple yarn spinning. The wave equation governing the twist propagation is solved by using the complex exponential representation of the rotating angle of a yarn cross-section. Provided that the influence of twist blockage is allowed to be ignorable, the solution of the wave equation can be formulated by the superposition of two counterpropagating waves: one twist wave propagating in the positive s direction with a velocity of v0 + v and the other one traveling along with the negative s direction with a velocity of v0 — v. The Doppler effect could be found in the twist propagation process. Further, the proposed method is applied in a false twisting process and a modified low-torque ring spinning frame. Finally, the corresponding twist distribution and the torques of twisting devices are derived.