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In this study, six groups of woven spacer fabrics with different structural parameters such as the spacer yarn pattern (V and W pattern) and spacer yarn density (denting pattern) were produced, and their compressional behaviour was investigated. According to the experimental results, the V-pattern spacer fabrics revealed better compressional resistance compared to the W-pattern spacer fabrics. Besides, it was observed that the spacer fabrics produced with lower spacer yarn density, were more susceptible to compressional forces. Statistical analysis of results demonstrated that all compressional parameters, except relative compressibility and thickness recovery, were affected by the spacer yarn pattern and density. Finally, the compressional behaviour of woven spacer fabric was correlated by three viscoelastic models (Kelvin model, Maxwell model, and three-component model with a nonlinear spring) and also the Van Wyk Theory. The results of curve fitting exhibited that the three-component model with nonlinear spring well fitted the experimental data. [ABSTRACT FROM AUTHOR]

Spacer fabrics are a category of 3D textiles and consist of two distinct fabrics which are connected together by spacer (pile) yarns. Spacer fabrics are produced by weaving, warp knitting and weft knitting systems and have many applications in different industries. The aim of this study was the production of woven spacer fabrics and analysis of their bending behavior. Thereafter, six different spacer fabrics were produced based on two variables: spacer yarn pattern and spacer yarn density. The resistance to bending of the spacer fabrics was measured based on the standard test method for evaluation of the fabric stiffness, by the circular bend procedure. In this regard, the maximum bending load and bending energy of spacer fabrics were recorded. The results showed that resistance to bending in spacer fabrics with V pattern of spacer yarns in the structure and also spacer fabrics with full threading of spacer yarns in the weaving reed was more than other kinds of spacer fabrics. By increasing the pile density and the number of spacer yarns, the fabric’s bending became more difficult. Statistical analysis of results at the confidence range of 95%, also revealed that the spacer yarn pattern and spacer yarn density have significant effect on bending resistance of spacer fabrics.

Stress relaxation is a time-dependent mechanical behavior in textiles. Textile deformations occurred as a result of stress relaxation, induces disturbances in textile function, and further disproportion between performance and application. Stress relaxation can be observed in pressure garments, varicose stockings, pressure bandages, etc. The aim of this study is to investigate the effect of miss stitch on the tensile stress relaxation of rib weft knitted fabrics. For this purpose, Rib fabrics with six different knit patterns differing in the number of miss stitches on successive rows were produced from 450/5 denier textured polyester yarn. The stress relaxation of the fabrics was measured in the course and wale directions under 20% strain for 30 minutes. The results revealed in all fabric structures, the stress created in the fabric decreases with time and that the amount of measured stress in both directions depends on the textile structure, as well as an increase in the number of miss stitches in the fabric structure leads to an increase in the initial stress, residual stress and stress relaxation of the fabric in the course and wale directions. Also, the values of the measured stress in the wale direction were higher than in the course direction.

Spacer fabrics are good candidates as cushioning materials in protective clothing and equipment. They demonstrate good compressive properties and energy absorption, which makes them suitable for human body protection. The cushioning performance of these fabrics is highly affected by the compression characteristics of the fabric. This research aims to improve the compression properties of spacer fabrics by incorporating elastic yarns with various tensions and alignments in the surface layers of the fabric. The results reveal that the presence of spandex yarn in the surface layers of the spacer fabric, as well as increasing the tension of spandex yarn, enhances the absorbed energy and dissipated compression energy while decreasing the resiliency, thickness change, and thickness recovery of the fabric. Moreover, increasing the number of miss stitches of spandex yarn decreases the energy absorption and dissipated compression energy while it increases the thickness change and thickness recovery of the fabric. Eventually, the utilization of elastic yarns under higher tension and fewer miss stitches in the surface layers of spacer fabrics improve the cushioning function of spacer fabrics. [ABSTRACT FROM AUTHOR]

Creep is one of the time-dependent mechanical behavior of textile materials, which can effect on the appearance and performance of the fabrics in various applications from garment to technical applications such as tensile structures and geotextiles. In the present study, the effect of fabric structure and loading direction on the creep behavior of two bar warp-knitted fabrics (Tricot, Reverse Locknit, 3 needle Sharkskin, 4 needle Sharkskin and Queen's cord) have been investigated. According to the results, the fabric structure and loading direction have outstanding influence on the creep of the fabrics. The creep of the fabric in the course direction decreases by increasing the length of underlaps in the back-guide bar, meanwhile increases in the wale direction. Moreover, Tricot and Revers Locknit structures demonstrated more creep in the course direction, whilst sharkskin 3, sharkskin 4 and Queen's cord structures exhibited higher creep values in the wale direction. Moreover, among considered fabric structures, Reverse Locknit with level of orthotropy near to1, revealed almost isotropic viscoelastic properties. [ABSTRACT FROM AUTHOR]

Bandages are a group of medical textiles that are available in various types for use in different applications such as wound dressing, compression therapy, treatment of burns, cramps, and sprains. In the present research, the structural and tensile characteristics of various medical bandages produced by different companies have been compared. According to the results, different bandages commercially sold under the same category demonstrate quite varied tensile properties, depending on their structure and constructional parameters. Consequently, compression bandages of the same type produced under different trade names would exert various amount of pressure to the body under constant stretch. In other word, various amount of stretch must be applied to different compression bandages to achieve and maintain the required pressure. Hence, to obtain better treatment outcomes, it is essential to provide the required information about the features of each medical bandage for the consumers. Furthermore, it was observed that the knitted compression bandages due to their higher stiffness (elastic modulus) provide higher pressure under minimum stretch in comparison with woven samples. Moreover, incorporation of higher number of stretch yarns to the bandage structure as well as using tighter structure increases the stiffness of the bandage, and in turn enhances the power of the bandage to cling on the limb for a longer period of time, in case of compression bandages. [ABSTRACT FROM AUTHOR]

Surgical mesh is a porous fabric, which is used for healing hernia, pelvic organ prolapse, and urinary incontinence. In the present study, synthetic surgical meshes with five different warp knitted structures, including Tricot, Pin hole-net, Sandfly, quasi-Sandfly, and quasi-Marqussite, have been fabricated using polypropylene monofilament, and the effect of loading direction on the stress relaxation of the meshes in orthogonal directions have been considered in comparison with human fascia. The results revealed that loading direction has a significant effect on the stress relaxation of the mesh. Different stress relaxation of various mesh structures in orthogonal directions can be attributed to the pore shape (pore angle) and underlap angle in the structure of the mesh. Except for Pin-hole-net mesh, all mesh structures displayed a constant and independent level of orthotropy to the relaxation time. Moreover, Tricot mesh and quasi-Sandfly mesh, with the level of orthotropy near to1, revealed almost isotropic viscoelastic properties. Overall, the quasi-Marqussite mesh was proposed as the most desirable surgical mesh due to its lighter weight, higher porosity, lower stress relaxation, and closest level of othotropy to the human fascia. [ABSTRACT FROM AUTHOR]

The behavior of the material against the external forces depends on its mechanical properties, including strength, elastic modulus, fatigue behavior, and so on. Of these properties, the elastic modulus has the highest importance and can be a criterion for describing the tensile elasticity or the tendency of a material to deform when opposing forces are applied along its axis. A wide range of test methods is available for measuring elastic modulus, but there is some uncertainty about the reliability of modulus values and can be addressed through good experimental and careful measurement. Among these methods, the tensile method is one of the most suitable methods for determining the elastic modulus of thin materials such as fibers. In this research, a new approach developed to calculate the elastic modulus based on the force-length curve to reduce the effects of common practical errors, like non-accurate measurement of the initial length and pretension of sample that shows the accuracy of new method. Three samples of yarn and fabric of different materials were tested for tensile strength. The linear part equation of the load-length curve was calculated and the elastic modulus values were determined according to the equation and Hooke's law. The standard deviation of the modulus in this method has been significantly reduced compared to the traditional mechanical method, also, the problems of pretension and initial length of the specimen have been resolved; Furthermore, using the new approach the initial length and strain values are obtainable with higher accuracy. [ABSTRACT FROM AUTHOR]

Surgical meshes as a replacement for the abdominal wall in hernia reconstruction are subjected to constant strain in the body. Thus, considering their stress relaxation is vital to ensure no recurrence of the disease. The aim of this study is to survey the influence of mesh structure and strain level on the stress relaxation of warp-knitted polypropylene meshes. To evaluate the stress relaxation of the meshes, a novel index named stress relaxation index was introduced. This index is obtained by multiplication of initial stress by the porosity of the mesh divided to the mass per unit area of the mesh. It was observed that mesh structure has remarkable effect on the stress relaxation of the meshes, and by increasing the stress relaxation index, stress relaxation increases. Furthermore, in all mesh structures, higher stress relaxation occurs in the meshes under higher tensile strain. Besides, among investigated rheological models, three components Maxwell model in parallel with nonlinear spring demonstrated the best fit to the experimental stress relaxation data. Eventually, quasi-Marquisette mesh structure suggested as the preferable mesh, owing to its lighter weight, higher porosity, and lower stress relaxation. [ABSTRACT FROM AUTHOR]

In this research the effect of surface layer knit pattern, and spacer yarn's inclination angle on the compression behavior of weft- knitted spacer fabrics made for cushioning applications have been investigated. The results reveal that fabric's compression resistance increases by increasing the spacer yarn's inclination angle as well as increasing the number of tuck stitches in successive courses in the surface layer. Moreover, by increasing the spacer yarn's inclination angle, the fabric's resilience, thickness change, and thickness recovery decrease, while the absorbed energy and dissipated compression energy increases. Furthermore, by increasing the number of tuck stitches in successive courses in the surface layer, the fabric's resilience as well as relative compressibility decreases, whilst the absorbed energy and dissipated compression energy increases. Eventually, spacer fabrics consist of knit stitches on their surface layers are more appropriate for cushioning applications due to higher energy absorption, and better resiliency and relative compressibility. [ABSTRACT FROM AUTHOR]

AbstractAuxetic materials are characterized by a negative Poisson’s ratio (NPR), which expands when stretched and shrinks when compressed. Due to the synclastic curvature of auxetics, they have good formability. These properties make them useful in applications requiring formability, such as composites, fashion and clothing, medical, protective, and sports fields. In this research, auxetic weft-knitted fabrics based on foldable structures were knitted. The effect of structural parameters including fabric pattern, yarn count, and loop length on the formability of auxetic weft-knitted fabrics was investigated and compared to plain weft-knitted fabric (Jersey). Auxetic fabrics with three distinct patterns and three different loop lengths were knitted using polyester yarns of varying three counts. Then, the formability experiment was conducted using the hemisphere mold, and the forming energy of fabric samples was obtained. The results demonstrated that auxetic fabrics exhibit superior formability to conventional (non-auxetic) fabrics, attributed to their synclastic curvature. Among the auxetic fabrics, those with larger zigzag angles, finer yarn counts, and larger loop lengths showed higher formability. These findings enhance the potential applications of auxetic fabrics in various industries such as medical and protective, emphasizing their ability to conform to complex shapes with minimal wrinkling. [ABSTRACT FROM AUTHOR]

Surgical mesh is a porous fabric that is mainly produced from polymeric monofilaments using the warp-knitting method. Surgical mesh is used for healing hernia. Among the mechanical properties of the mesh, tensile and bursting strength have special significance. In this research, warp-knitted surgical meshes with five structures have been produced using polypropylene monofilament, and the effect of the fabric structure on the bursting characteristics of them has been investigated. All the meshes exhibited supraphysiologic bursting strength. quasi-Sandfly mesh demonstrated the highest, while quasi-Marqussite mesh exhibited the least bursting characteristics. The increase in the bursting characteristics of the meshes is attributed to the increase in the areal density and decrease in the porosity of them. Moreover, conformity between the bursting and tensile properties of them in bias direction has been observed. Overall, quasi-Marqussite mesh was proposed as the most desirable mesh in terms of porosity, weight, and bursting characteristics. [ABSTRACT FROM AUTHOR]

Lateral compression is one of the most important mechanical aspects of fabrics, which reflects their handle. Fabric compressional features depend on the compressional characteristics of constituent yarns and the fabric structure. In order to consider the effect of fabric structural parameters on its compressional properties, woven fabrics with five different weave patterns (plain, hopsack 2/2, twill 2/2, twill 3/1, warp rib 2/2) were produced with three different nominal weft densities (12, 15, 18 cm−1). The compressional properties of produced fabrics were evaluated at different pressure values using a conventional fabric thickness tester. It was observed that increasing the weft density leads to decrease in the dissipated compression energy as well as the compressibility of the fabric, while the thickness recovery of the fabric increases. Moreover, the plain woven fabric exhibited the lowest dissipated compression energy and compressibility, while the highest thickness recovery. Besides, at the low pressure level, the fabrics with the lower weft densities demonstrate the higher thickness. By increase in the pressure level, the fabric thickness decreases by decreasing the weft density. [ABSTRACT FROM AUTHOR]

The yarn pullout test is a prevailing and particular method to evaluate the effects of yarn properties and the structural characteristics of the fabric on the fabric mechanical performance. In this research, a theoretical model of yarn pull out is presented to determine the reserved energy of weft-knitted fabrics with rib 1 × 1 structure. This model is based on the fabric dimensional properties, i.e. stitch length, wale density, yarn diameter and contact angle of yarns. In order to appraise the proposed model, five different double jersey weft-knitted fabrics with rib 1 × 1 structure were produced and exposed to pullout test. Comparison between deviations of theoretical results from experimental results demonstrates that the presented theoretical model exhibits a rational estimation of the reserved energy in these fabrics. [ABSTRACT FROM AUTHOR]

When strain is applied constantly, there is a decreased stress with time in viscoelastic materials, which is called stress relaxation. During the manufacture and application of clothing and footwear, materials experience various long-lasting deformations, and relaxation process in materials arises. Thus, with theoretical and experimental study of the factors affecting stress relaxation, the ability to design and produce appropriate clothes will be increased. In the first part of this research, we studied the stress relaxation behavior of warp-knitted structures which have longer underlaps in back bar (reverse locknit, three- and four-needle sharkskin, and queens’ cord). Following the previous research, the aim of this study was to investigate the effect of fabric structure, strain percentage, and course density on the stress and stress relaxation of the warp-knitted structures which have longer underlaps in front bar (locknit, three- and four-needle satin, and loop raised). The results reveal that the fabric structure, strain value, and fabric density are important factors affecting the stress and stress relaxation percent of the fabrics. By increasing the strain and the length of underlap in the front guide bar, stress and stress relaxation percent will be increased. Also, fabrics with higher course density show higher stress and stress relaxation percent. Among the mechanical models used to describe the stress relaxation behavior of the fabrics, the three-component Maxwell’s model with parallel-connect nonlinear spring showed the best agreement with the experimental stress relaxation curves of the analyzed fabrics. [ABSTRACT FROM PUBLISHER]

Time-dependent mechanical behavior of textiles has particular importance. One of such behaviors is the stress relaxation. If a fabric is under tension over a period of time, some of the stresses in it will be relieved. During the manufacture and application of clothing and footwear, materials experience various long-lasting deformations, and relaxation process in materials arises. For example, if medical pressure garments such as compression stockings are under tension over a long period of time, some of their stresses will be relieved, with a consequent reduction in the skin and garment interfacial pressure. Thus, with theoretical and experimental study of the factors affecting stress relaxation, the ability to design and produce appropriate clothes will be increased. The aim of this study was to investigate the effect of fabric structure on the stress relaxation of two bar warp-knitted fabrics (reverse locknit, sharkskin, queens’ cord), as well as to find the effect of strain value and loading direction on the stress relaxation of the fabrics. The results reveal that the fabric structure, strain, and loading direction are important factors affecting the stress and stress relaxation percent of the fabrics. By increasing the strain and the length of underlap in the back guide bar, stress will be increased, but stress relaxation percent will be decreased. Also, stress relaxation percent in wale direction is more than course direction for reverse locknit and sharkskin3, but this is reversed for sharkskin4 and queens’ cord. Finally, among the mechanical models used to describe the stress relaxation behavior of the fabrics, three-component Maxwell’s model with parallel-connect nonlinear spring showed the best agreement with the experimental relaxation curve of the analyzed fabrics. [ABSTRACT FROM AUTHOR]

This study focuses on the theoretical and experimental creep behavior of plain woven fabrics using the yarn creep property and the structural--mechanical parameters of the fabric. For this purpose, two viscoelastic models, i.e. the Kelvin model in series with a spring and the Eyring model, were developed as a theoretical analysis to predict the fabric elongation while subjected to a constant load. Then, the theoretical results from these models were compared with experimental results for fabrics of different weft densities. It was obtained that the later model shows closer results to the experimental creep than earlier model. It was also found that an increase in weft density leads to a decrease in fabric creep. [ABSTRACT FROM AUTHOR]

The effect of yarn twist on the wicking rate of cotton interlock weft knitted fabrics has been studied. It is observed that using the yarn linear density of 30tex, the wicking rate decreases with an increase in the amount of yarn twist. An equation 'h=cT+d' is found to be a good estimate of the maximum wicking height (h) for cotton interlock weft knitted fabrics measured over yarn twist (T). Also, an equation 'h=atk+bt' which is a modified version of Washburn-Laughlin's equation, is a good estimate of wicking height (h) for these fabrics measured over time (t). [ABSTRACT FROM AUTHOR]