Warp-knitted Fabrics Research Articles

Directionally Oriented Reinforcements of Warp-Knitted Fabrics for Composite Preforms

This paper focuses on the development of a methodology for the directional structural modification of warp-knitted fabrics by sewing on carbon fiber tapes. Four-, five-, and six-axial geometric systems were designed to optimize the qualitative distribution of stresses on the surface of the tested product. Through a numerical experiment in the ANSYS environment, the impact of the change in the axiality of a textile structure on the mechanical properties of the modeled geometric configuration was assessed. This analysis was experimentally verified by measuring the multiaxial force distribution on the knitted surface, which demonstrated that Variant 7, with six axes 30° apart, was the most favorable.

Automated model discovery for textile structures: The unique mechanical signature of warp knitted fabrics

Textile fabrics have unique mechanical properties, which make them ideal candidates for many engineering and medical applications: They are initially flexible, nonlinearly stiffening, and ultra-anisotropic. Various studies have characterized the response of textile structures to mechanical loading; yet, our understanding of their exceptional properties and functions remains incomplete. Here we integrate biaxial testing and constitutive neural networks to automatically discover the best model and parameters to characterize warp knitted polypropylene fabrics. We use experiments from different mounting orientations, and discover interpretable anisotropic models that perform well during both training and testing. Our study shows that constitutive models for warp knitted fabrics are highly sensitive to an accurate representation of the textile microstructure, and that models with three microstructural directions outperform classical orthotropic models with only two in-plane directions. Strikingly, out of 214=16,384 possible combinations of terms, we consistently discover models with two exponential linear fourth invariant terms that inherently capture the initial flexibility of the virgin mesh and the pronounced nonlinear stiffening as the loops of the mesh tighten. We anticipate that the tools we have developed and prototyped here will generalize naturally to other textile fabrics–woven or knitted, weft knit or warp knit, polymeric or metallic–and, ultimately, will enable the robust discovery of anisotropic constitutive models for a wide variety of textile structures. Beyond discovering constitutive models, we envision to exploit automated model discovery for the generative material design of wearable devices, stretchable electronics, and smart fabrics, as programmable textile metamaterials with tunable properties and functions. Our source code, data, and examples are available at https://github.com/LivingMatterLab/CANN. Statement of significanceTextile structures are rapidly gaining popularity in many biomedical applications including tissue engineering, wound healing, and surgical repair. A precise understanding of their unique mechanical properties is critical to tailor them to their specific functions. Here we integrate mechanical testing and machine learning to automatically discover the best models for knitted polypropylene fabrics. We show that warp knitted fabrics possess a complex symmetry with three distinct microstructural directions. Along these, the behavior is dominated by an exponential linear term that characterize the initial flexibility of the virgin mesh and the nonlinear stiffening as the loops of the fabric tighten. We expect that our technology will generalize naturally to other fabrics and enable the robust discovery of complex anisotropic models for a wide variety of textile structures.

Physicochemical Properties of Warp Knitted Fabrics Colored with Madder and Gall Oak for Sportswear

ABSTRACT Polyamide/elastane warp-knitted fabrics were separately dyed with gall oak (Quercus infectoria Olivier) and madder (Rubia tinctorum L.). Chromatographic and spectroscopic methods were used to analyze dyed warp-knitted fabrics. A reserved phase high-performance liquid chromatography with the diode-array detection (RP-HPLC-DAD) method was utilized to determine the components of dyes present in the dyed fabrics. Scanning electron microscopy-energy X-ray spectroscopy (SEM-EDX) was utilized for morphological analysis. The undyed and dyed warp-knitted fabrics were characterized by FT-IR. The CIEL*a*b* values of the dyed polyamide-elastane warp-knitted fabrics were measured. Further, in physical testing, the pilling and abrasion resistance of raw and dyed fabrics were examined, and the water contact angle values of all fabrics were measured. Pilling test results were evaluated with a grade of 5 for all fabrics as the best score, and the resistance of fabrics to abrasion was very good. The formation of the fiber-metal-dye complex caused the fabric’s contact angle to drop, giving the fabric a hydrophilic character. The colorfastness characteristics of the dyed fabrics to light, rub, wash, and perspiration have been evaluated. The light fastness scores vary from 3 to 5, and they are satisfactory for using natural dyes to color textiles since they are in the good to moderate range. Overall, the dyed samples displayed a score of 5, which is excellent, on the Gray Scale for washing fastness.

Thermoelectric generator modules based on warp knitted glass fiber-metal hybrid composites

Thermoelectric generators (TEG) offer the potential to convert waste heat into electricity and thus contribute to reduce CO2 emissions. The conversion of electrical energy is based on the Seebeck effect of two electrically conductive materials without any mechanical conversion and therefore without wear. The application of conventional TEG modules is limited due to cost-intensive materials and production technology of TEG, and a limited structure design for the integration of Thermoelectric Elements (TE). To address this research challenge, this work presents the development of thermoelectric composite modules based on glass fiber reinforced warp knitted spacer fabrics. In a double needle bed warp knitting machine, glass fibers in warp, weft and pile direction are integrated. The contacting of TE in the form of wires with 45 TE cm−2 were implemented. A TEG module with 20.25 cm2 in size showed a maximum output power of 2.7 μW at a temperature difference of 60 K. The Seebeck factor of S = 142 μV K−1 was determined using this composite TEG with 10 TE strands and nearly 400 thermocouples. A thermoelectric model was developed for the calculation and the modules were characterized. For the first time, thermoelectric composite modules with sufficient structural-mechanical properties in terms of compressive and bending stiffness were realized based on spacer warp knitted fabrics, which can be used for the operation of sensors or small devices.

Optimization of mechanical property and microstructure for magnesium phosphate cement-based canvas using borax

As a type of excellent rapid protective material with fast hardening and high early strength characteristics, magnesium phosphate cement (MPC) is used as the cementitious material to fabricate concrete canvas. For a thick MPC canvas, sufficient hydration reaction is crucial in keeping its integrity. Borax is used to adjust the hydration progress of MPC in warp-knitted fabrics. The effects of different borax contents (0 %, 1 %, 2 %, 3 %, 4 %, 5 %, 6 %) on the compactness of reaction products and the mechanical properties of MPC canvas are evaluated. In addition, SEM, XRD, hydration heat, and X-CT are used to systematically analyze the hydration morphology, products, exothermic process, and pore structure of MPC canvas. The results show that borax can effectively delay the setting time of MPC, addressing the issue of incomplete hydration of MPC powder in thick canvas. The 4 % borax content (B4 sample) can ensure the complete reaction in a 20 mm thick MPC canvas, achieving the maximum compressive and flexural strengths of 26.37 MPa and 4.9 MPa at 7 d, respectively. Borax effectively optimizes the pore structure of MPC canvas and achieves a dense bond at the interface between MPC and the canvas fabric with the minimum porosity of 11 % in the B4 sample. Therefore, borax is crucial for ensuring the structural integrity of MPC canvas.

Early Clinical Results for a New Self-Organizing Hybrid Fabric in Congenital Cardiac Surgery

BackgroundWe have developed a new hybrid warp-knit fabric for induction of in situ tissue regeneration that has shown appropriate antideterioration properties and expandability in preclinical studies. This study was performed to assess the clinical efficacy and safety of this fabric in the early postoperative period after congenital cardiac surgery. MethodsThe fabric comprises biodegradable (complete degradation period, 2-3 years) and nonbiodegradable yarns coated with cross-linked gelatin. A multicenter single-arm 3-year study was conducted. The primary end point for regulatory approval was the surgical success rate without death or reintervention related to fabric failure at 1 year after surgery. Secondary end points included the incidence of material-related secondary lesions. ResultsThe fabric was implanted at 41 sites (pulmonary artery, n = 18; right ventricular outflow tract, n = 12; atrial septum, n = 7; and ventricular septum, n = 4) in 34 patients of median age 1 year 11 months (range, 4 months-58 years). The surgical success rate was 100%. There were no abnormal findings for the fabric on echocardiography and no serious adverse events in a median follow-up period of 40 months (range, 36-55 months), other than 3 stenotic lesions that were due to the surgical procedure. These results permitted regulatory approval for use of the fabric in Japan. ConclusionsThe new fabric promoting tissue self-organization through a novel technology showed acceptable efficacy and safety in the early postoperative period after congenital cardiac surgery.

High-stability flexible body motion monitoring sensor based on waterborne polyurethane-coated conductive warp-knitted fabric

High-stability flexible body motion monitoring sensor based on waterborne polyurethane-coated conductive warp-knitted fabric

In‐plane compressive properties and failure mechanisms of modified three‐dimensional multi‐axial warp knitted fabrics reinforced composites at different temperatures

AbstractThree‐dimensional multi‐axial warp knitted (3D MWK) reinforced composites are important components of advanced structural composites. The interfacial bonding between fiber and matrix is key to achieving high mechanical properties. In this work, graphene oxide (GO) and poly(oxypropylene) diamines (D400) were grafted on glass fiber (GF) multi‐axial warp knitted (MWK) fabrics to construct a “flexible‐rigid” structure. The surface morphologies of GF were characterized by SEM and EDS. Then, 3D MWK‐reinforced composites were prepared based on four kinds of modified fabrics using the VARTM method. The in‐plane compression properties were obtained at different high temperatures and their failure modes were analyzed. The strain–stress curves showed that the composites exhibited brittle fracture modes. D400 and GO‐modified multi‐scale composites exhibited outstanding compression properties. The strength of the related composited was improved by 55.78%, 76.78%, 52.19%, and 56.78% compared to that of desized composite at 30°C, 60°C, 120°C and 150°C, respectively. The damage to D400‐GO modified and D400 modified composites was the most serious, where shear fracture modes were obvious in addition to layer debonding features. This protocol provides a potential strategy to manufacture of D400 and GO‐modified hierarchical reinforced composites.Highlights The modified 3D MWK glass fabrics based on poly(oxypropylene) diamines (D400) and graphene oxide (GO) were prepared. The compressive properties of 3D desized, D400‐, D400‐GO‐, and GO‐MWK fabrics reinforced epoxy composites were obtained and analyzed at different temperatures of 30°C, 60°C, 120°C, and 150°C. The failure mechanisms of 3D desized, D400‐, D400‐GO‐, and GO‐MWK fabrics reinforced epoxy composites at different temperatures were analyzed.

Study on Motion Sensing Using Textile Electrodes-Focusing on the Application of PANI Conductive Material

Abstract This study investigates the application of textile electrodes using PANI (Polyaniline) conductive material for motion sensing, specifically aimed at motion monitoring for the elderly. By depositing a PANI conductive layer on the base of warp-knitted fabric through in-situ polymerization and plasma treatment, a PCCWKF (Polyaniline Coated Conductive Warp-Knitted Fabric) with enhanced electrical conductivity and mechanical flexibility was developed. The research optimized the electrical resistivity and durability of PCCWKF by incorporating Polyvinyl Alcohol (PVA) as a toughening agent, improving the adhesion of the PANI conductive layer to the textile substrate. The sensor’s efficacy in accurately recording and monitoring motion amplitude and frequency in real-time was demonstrated through its application in smart clothing, focusing on respiratory, elbow, and knee motion monitoring. This study holds significant implications for the advancement of wearable technology and smart textiles in the health monitoring of the elderly.

Design and manufacture of hybrid mesh for hernia treatment

The warp knitting method is typically used to create hernia mesh. It can add new qualities to the meshes due to the formation of micro/nanofibers, cell proliferation, biocompatibility, non-adhesion, and drug release properties. Within the purview of this work, warp-knitted mesh (polypropylene) with micro/nanofibers was created. On this constructed mesh structure, silk fibroin/polyurethane/levan/curcumin fibers were produced using the centrifugal jet spinning technique. When SEM images were examined, the average fiber diameter was 932 ± 407 nm, and the pore diameter was 20 µm. The nanofiber warp-knitted fabric was measured to have a bursting strength of 182.9 ± 11 kPa. It was determined that the abdominal wall’s predicted elasticity value of 15.65% horizontally was enough for both men and women. It was determined that the hybrid mesh structure performed better against E.coli bacteria and that the curcumin-infused mesh had an antibacterial effect. It was found that meshes might be employed as hybrid meshes for the treatment of hernias.

Design and simulation of warp knitted fabrics using MATLAB: a framework for cleaner production

Design and simulation of warp knitted fabrics using MATLAB: a framework for cleaner production

Mechanical properties of flexible composites reinforced with high-performance glass fiber multi-axial warp-knitted fabrics

This paper investigates the quasi-static mechanical properties and damage behavior of flexible composites prepared from high-performance glass fiber-based multi-axial warp knitted fabrics as reinforcement and high tenacity environmentally friendly thermoplastic polyurethane as a matrix. The composites were produced by attaching thermoplastic polyurethane (TPU) to the top and bottom of the fabric using a vulcanization machine, followed by hot-pressing for different temperatures and time settings. Moreover, the effects of different preparation processes on the tensile strength, static puncture resistance, and tear strength of flexible composites were investigated in this paper. The results indicated that both hot-pressing temperature and vulcanization time had a significant impact on the mechanical properties of the composites. With an optimum vulcanization temperature of 185°C and a vulcanization time of 10 min, the composite provides optimum tensile strength and puncture resistance. Tear strength is the worst and is related to the reinforcement’s organisational structure and the interfacial bond’s strength. The results of this study are of theoretical and practical significance for applying high-performance multi-axial warp-knitted flexible composites as raw materials in the construction field.

Study of physical, moisture-management and stretch properties of underwear fabrics

This study investigated and characterized the physical properties and their influence on moisture management and stretch properties of underwear fabric made of different compositions of fibres. It is found that fabric made of finer filament yarn, having an open and porous structure, smaller stich length, and smaller thickness has higher air permeability, water vapour permeability, better moisture transport and overall moisture management capacity. It is also found that elastic recovery is higher in the wale direction in the case of weft-knitted fabrics. Furthermore, a fabric with longer stich length has higher stretch in both directions and more recovery in the wale direction. In addition, it is found that warp-knitted fabric has better moisture transport.

Research on the Defect Detection Algorithm of Warp-Knitted Fabrics Based on Improved YOLOv5

Research on the Defect Detection Algorithm of Warp-Knitted Fabrics Based on Improved YOLOv5

The Moisture Management Property of Innovative Two-Layered Tricot Warp Knitted Fabric

The Moisture Management Property of Innovative Two-Layered Tricot Warp Knitted Fabric

The effect of weft yarn type and elastomer yarn threading on the properties of elastic warp knitted fabrics. Part II: Thermal comfort properties

The aim of this study is to determine the performance properties of elastic warp-knitted fabrics used for medical purposes. The samples were knitted using different weft yarn material and changing the threading order of elastomer yarn. The detailed results of the dimensional and elasticity performance of elastic warp-knitted fabrics had been reported in Part I of this series. In this part, the effects of weft yarn material and the threading order of elastomer yarn on the thermal comfort characteristics were investigated. It has been seen that the type and linear density of the transverse weft yarns and the number of elastomer yarns in the fabric structure affected significantly the thermal comfort and permeability characteristics of the developed elastic warp-knitted fabrics. According to the results, using polyester yarns as weft and reducing the number of elastomer yarns led to an increase in air permeability. Additionally, the thermal conductivity characteristics of the fabrics increased as the number of elastomer yarns in the structure increased. It has been seen that from the results, the water vapour resistance coefficient of the samples is appropriate for the usage of these fabrics in medical products.

Uniaxial tensile strain correction of multi-axial warp-knitted fabric

This paper analyzes the error between the theoretical calculated and actual values of single inserting yarn strain of multi-axial warp-knitted fabric under the uniaxial stretching process, and the “open M-shaped curved surface” of error was obtained theoretically. The analysis results show that the error increases with the increase of fabric elongation. The error is smaller in the small deformation range (fabric maximum elongation is 5%) and larger in the large deformation range. In addition, the error is also related to the angle between the single inserting yarn axis and the uniaxial tensile direction. The error varies periodically with the angle ([Formula: see text]), reaching its maximum when it is close to [Formula: see text]. In order to realize the correction of the existing theoretical calculated formula of single inserting yarn strain, the error formula was fitted by combining the laws of errors. The correction of the single inserting yarn strain was successfully achieved by the fitted error formula. The correction equation can correct the inserting yarn at any angle in the fabric strain range of 0–50%. The correction equation has a larger range of use and more accurate results than the theoretical calculated formula for inserting yarn. Finally, the validation was carried out with bias inserting yarn at [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] angles and the results were very good. Therefore, the corrected equation can replace the actual value of bias inserting yarn strain.

Study on Flexural Behaviour of Ferrocement Composites Reinforced with Polypropylene Warp Knitted Fabric.

Ferrocement is a cost-effective construction material used in the low-cost constructions. It is produced with the combination of cement mortar with closely spaced wire mesh known as chicken wire mesh. Ferrocement process eliminates coarse aggregates when compared to reinforced concrete thus makes the process simple. This paper deals with the influence of various characteristics of warp knitted fabric on the flexural properties of ferrocement composites. Ferrocement composites have a wide range of applications in the construction industry and it has some limitations due to the durability issues. Among the various durability issues, corrosion is one of the main issues to be addressed to enhance the long-term service life of the ferrocement composites. The idea of using non-metallic mesh to eliminate the corrosion problem is discussed in this paper. In this experiment, warp knitted fabric reinforced ferrocement composites were produced using polypropylene warp knitted fabrics. This paper deals with the flexural properties of ferrocement composites made of warp knitted fabric coated with expoxy. This paper deals with the flexural properties of ferrocement composites made of warp knitted fabric coated with expoxy. These composites were analyzed for their flexural strength, energy absorption and ductile property. The variables in the experiment are filament thickness, warp knitted structure and number of layers in the composites. Experimental results proved that the replacement of chicken mesh wire by warp knitted fabrics has an impact in the flexural properties of the composites and the effect of variables in the experiment set up has been analyzed. There is an imporvement of 200% is observed in the first crack load and 120% improvement in the ultimate load of the warp knit fabric reinforced composite compared to control sample. Experimental results proved that there is an increase in flexural strength of ferrocement composites made up with warp knitted fabrics. Microstructure studies like SEM and EDX on ferrocement laminates confirmed good bonding between the mortar mix and warp knitted fabrics.

Off-axis tearing properties of the biaxial warp-knitted fabrics

This study presents an experimental and analytical investigation of the tearing properties of the biaxial warp-knitted fabrics with different off-axis angles. Firstly, the off-axis tensile tests, central tearing tests, single edge notch tearing tests, and trapezoidal tearing tests were carried out at seven off-axis angles. The strength, failure mode, and failure mechanism of the specimens under each test condition were studied. The results show that in the off-axis tensile tests, the lowest values of the tensile strength of the biaxial warp-knitted fabrics appear at the off-axis angles of 15° and 75° rather than the conventional 45°. Under the coupling effect of tensile strength and shearing strength, the yarn layers peeling occurs instead of yarn fracture, which is a unique failure mode of biaxial warp-knitted fabrics. The yarns of the biaxial warp-knitted fabrics can fully deform to balance the load due to the warp-knitting method, which improves the tearing strength and makes the failure brittle.

A novel method for evaluating the tensile behavior isotropy of surgical meshes based on the analysis of the polar graph of tensile properties using image processing method

The most common hernia treatment method is using a surgical mesh. The functional properties of surgical meshes, including structural and mechanical properties affect mesh performance. Anisotropy of the tensile behavior of the surgical mesh influences the hernia treatment process. In this research, a novel index named ‘isotropy index’ is introduced based on the analysis of the polar graph of the tensile properties of surgical meshes. The isotropy index, which is expressed in percent, was defined as the ratio of the polar diagram area of the tensile elastic modulus to the area of the circle surrounding the polar graph and calculated using the meshes' tensile elastic modulus in five directions(0°(course), 30°, 45°, 60°, and 90°(wale)) using the image processing method. For this purpose, common net warp-knitted fabrics in surgical mesh production were produced with five various knit patterns(quasi-Sandfly, Tricot, Pin-hole-net, Sandfly, and quasi-Marqussite) using polypropylene monofilament yarns, and their tensile properties were analyzed in various directions(0°(course), 30°, 45°, 60°, and 90°(wale)). Results revealed that the quasi-Sandfly mesh is the most isotropic(57.74%), and the quasi-Marqussite mesh is the most anisotropic(17.12%) among evaluated surgical meshes. Tricot mesh(54.98%), Sandfly mesh(49.17%), and Pin-hole-net mesh(46.41%) in terms of the tensile behavior isotropy are between quasi-Sandfly mesh and quasi-Marqussite mesh. The Sandfly mesh has the closest isotropy index to the abdominal wall tissue. Considering the importance of the lightness, adequate porosity, larger pore size, and closeness of the mesh’ isotropy index to abdominal wall tissue for enhancing mesh functional properties, the Sandfly mesh was selected as the best-knit pattern for surgical mesh.