Search Results (36)

This study investigates the mechanical, morphological, and wear properties of SiO₂-filled tri-axial warp-knitted (TWK) glass fiber-reinforced vinyl ester matrix composites, with a focus on void fraction, tensile, flexural, hardness, and wear behavior. Adding SiO₂ fillers reduced void fractions, enhancing composite strength, with values ranging from 1.63% to 5.31%. Tensile tests revealed that composites with 5 wt% SiO₂ (GV1) exhibited superior tensile strength, Young’s modulus, and elongation due to enhanced fiber–matrix interaction. Conversely, composites with 10 wt% SiO₂ (GV2) showed decreased tensile performance, indicating increased brittleness. Flexural tests demonstrated that GV1 outperformed GV2, showcasing higher flexural strength, elastic modulus, and deflection, reflecting improved load-bearing capacity at optimal filler content. Shore D hardness tests confirmed that GV1 had the highest hardness among the specimens. SEM analysis revealed wear behavior under various loads and sliding distances. GV1 exhibited minimal wear loss at lower loads and distances, while higher loads caused significant matrix detachment and fiber damage. These findings highlight the importance of optimizing SiO₂ filler content to enhance epoxy composites’ mechanical and tribological performance. Full article

This study presents the development of a textile-based cascade filter for the removal of microplastics from an industrial laundry effluent. The cascade microfilter consists of three stages of 3D textile sandwich composite filter media, which have successively finer pores and are aimed at filtering microplastic particles down to 1.5 µm. Polypropylene fabrics with pore sizes of 100, 50 and 20 µm and 3D warp-knitted fabrics with high porosity (96%) were used. Filtration tests were carried out with polyethylene model microplastic particles at a concentration of 167 mg/L. To regenerate the filter and restore its filtration performance, backwashing with filtered water and compressed air was applied. Field trials at an industrial laundry facility and a municipal wastewater treatment plant confirmed high removal efficiencies. The 3D textile sandwich structure promotes filter cake formation, allowing extended backwash intervals and the effective recovery of filtration capacity between 89.7% and 98.5%. The innovative use of 3D textile composites enables a high level of microplastic removal while extending the filter media lifetime. This makes a significant contribution to the reduction in microplastic emissions in the aquatic environment. The system is scalable, space and cost efficient and adaptable to various industrial applications and is thus a promising solution for advanced wastewater treatment. Full article

This study presents new, knitted fabrics that combine woven and knitted structures to better control compression garments. This can be achieved by incorporating inlay yarns that utilize a woven configuration within knitted fabrics. As a result, this structure enhances the fabric’s functionality. Central to the research is the development and evaluation of various prototypes of arm sleeves using nylon–spandex, specifically engineered to apply the desired pressure on arms. The sleeves were knitted using different base structures including single jersey, single pique, 1 × 1 mock rib, and 2 × 2 mock rib, with and without inlays. A commercial sleeve was added as a reference. According to the protocol, the applied pressure of each sleeve was measured at three different points on the dominant arm of 12 healthy females. Stretch properties of arm sleeves were examined using an elongation tester. The thickness and weight of fabrics were evaluated as well. Also, the results of surveys—featuring four questions about the ease of motion, softness, thermal sensation, and overall comfort—were statistically analyzed. The analysis showed that the commercial and 2 × 2 mock rib sleeves were the most comfortable, creating pleasant subjective wearing sensations. The findings showed that the fabric’s tensile properties were significantly changed by the inclusion of inlay yarns in the weft and warp directions. According to survey results, 1 × 1 mock rib and 1 × 1 mock rib with inlay negatively affected subjective wearing sensations, while exerting the highest pressure on the subject’s arm. This is associated with the fabric’s compressive structure which directly contributes to the increased thickness and weight of the fabric. Full article

In order to improve the accuracy and detection effect of fabric defect detection, a fabric defect detection method based on local similarity comparison is proposed in this paper. This method first takes each pixel in the image as the central pixel, selects a specific window as the region size, and then uses the similarity between the central region and the surrounding neighborhood to find the neighborhood most similar to the central region to complete the estimation of the central pixel. Finally, the target image is obtained by the principle of background difference, so as to detect fabric defects. The results show that this method is superior to the traditional detection method, which can not only detect the defect image under the complex background, but also have good detection results for the fabric defect image under the influence of different organization and lighting factors. The detection accuracy rate under factory conditions can reach 98.45%, which has a high applicability and detection rate, and also demonstrates certain anti-interference performance. Full article

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. Full article

Physical therapy is often essential for complete recovery after injury. However, a significant population of patients fail to adhere to prescribed exercise regimens. Lack of motivation and inconsistent in-person visits to physical therapy are major contributing factors to suboptimal exercise adherence, slowing the recovery process. With the advancement of virtual reality (VR), researchers have developed remote virtual rehabilitation systems with sensors such as inertial measurement units. A functional garment with an integrated wearable sensor can also be used for real-time sensory feedback in VR-based therapeutic exercise and offers affordable remote rehabilitation to patients. Sensors integrated into wearable garments offer the potential for a quantitative range of motion measurements during VR rehabilitation. In this research, we developed and validated a carbon nanocomposite-coated knit fabric-based sensor worn on a compression sleeve that can be integrated with upper-extremity virtual rehabilitation systems. The sensor was created by coating a commercially available weft knitted fabric consisting of polyester, nylon, and elastane fibers. A thin carbon nanotube composite coating applied to the fibers makes the fabric electrically conductive and functions as a piezoresistive sensor. The nanocomposite sensor, which is soft to the touch and breathable, demonstrated high sensitivity to stretching deformations, with an average gauge factor of ~35 in the warp direction of the fabric sensor. Multiple tests are performed with a Kinarm end point robot to validate the sensor for repeatable response with a change in elbow joint angle. A task was also created in a VR environment and replicated by the Kinarm. The wearable sensor can measure the change in elbow angle with more than 90% accuracy while performing these tasks, and the sensor shows a proportional resistance change with varying joint angles while performing different exercises. The potential use of wearable sensors in at-home virtual therapy/exercise was demonstrated using a Meta Quest 2 VR system with a virtual exercise program to show the potential for at-home measurements. Full article

Warp knitting is a highly productive textile manufacturing process and method of choice for many products. With the current generation of machines running up to 4400 min⁻¹, dynamics become a limit for the production. Resonance effects of yarn-guiding elements and oscillations of the yarn lead to load peaks, resulting in breakage or mismatches. This limits material choice to highly elastic materials for high speeds, which compensate for these effects through their intrinsic properties. To allow the processing of high-performance fibers, a better understanding of the viscoelastic yarn behavior is necessary. The present paper shows a method to achieve this in longitudinal yarn direction using a dynamic mechanical analysis approach. Samples of high tenacity polyester and aramid are investigated. The test setup resembles the warp knitting process in terms of similar geometrical conditions, pre-loads, and occurring frequencies. By recording the mechanical load resulting from an applied strain, it is possible to calculate the phase shift and the dissipation factor, which is a key indicator for the damping behavior. It shows that the dissipation factor rises with rising frequency. The results allow for a simulation of the warp knitting process, including a detailed yarn model and representation of stitch-formation process. Full article

Cardiovascular disease is a major threat to human health worldwide, and vascular transplantation surgery is a treatment method for this disease. Often, autologous blood vessels cannot meet the needs of surgery. However, allogeneic blood vessels have limited availability or may cause rejection reactions. Therefore, the development of biocompatible artificial blood vessels is needed to solve the problem of donor shortage. Tubular fabrics prepared by textile structures have flexible compliance, which cannot be matched by other structural blood vessels. Therefore, biomedical artificial blood vessels have been widely studied in recent decades up to the present. This article focuses on reviewing four textile methods used, at present, in the manufacture of artificial blood vessels: knitting, weaving, braiding, and electrospinning. The article mainly introduces the particular effects of different structural characteristics possessed by various textile methods on the production of artificial blood vessels, such as compliance, mechanical properties, and pore size. It was concluded that woven blood vessels possess superior mechanical properties and dimensional stability, while the knitted fabrication method facilitates excellent compliance, elasticity, and porosity of blood vessels. Additionally, the study prominently showcases the ease of rebound and compression of braided tubes, as well as the significant biological benefits of electrospinning. Moreover, moderate porosity and good mechanical strength can be achieved by changing the original structural parameters; increasing the floating warp, enlarging the braiding angle, and reducing the fiber fineness and diameter can achieve greater compliance. Furthermore, physical, chemical, or biological methods can be used to further improve the biocompatibility, antibacterial, anti-inflammatory, and endothelialization of blood vessels, thereby improving their functionality. The aim is to provide some guidance for the further development of artificial blood vessels. Full article

Fibre-reinforced composites (FRCs) are already well established in several industrial sectors such as aerospace, automotive, plant engineering, shipbuilding and construction. The technical advantages of FRCs over metallic materials are well researched and proven. The key factors for an even wider industrial application of FRCs are the maximisation of resource and cost efficiency in the production and processing of the textile reinforcement materials. Due to its technology, warp knitting is the most productive and therefore cost-effective textile manufacturing process. In order to produce resource-efficient textile structures with these technologies, a high degree of prefabrication is required. This reduces costs by reducing the number of ply stacks, and by reducing the number of extra operations through final path and geometric yarn orientation of the preforms. It also reduces waste in post-processing. Furthermore, a high degree of prefabrication through functionalisation offers the potential to extend the application range of textile structures as purely mechanical reinforcements by integrating additional functions. So far, there is a gap in terms of an overview of the current state-of-the-art of relevant textile processes and products, which this work aims to fill. The focus of this work is therefore to provide an overview of warp knitted 3D structures. Full article

Shell-rib structures made of textile-reinforced composites are used in a wide range of applications to increase bending, buckling and torsional stiffness. Such composites are usually manufactured in differential construction at the preform level by assembling several textile structures or at the component level by the subsequent joining of separately manufactured shells and stiffening structures. Integral preform production is one way to overcome the disadvantages of the forenamed methods, such as high manual effort, failure during assembling or fiber distortion. Weft-knitting technology is excellent for achieving integral preforms for shell-rib components with a strong connection between the shell and the rib, especially while producing biaxial weft-knitted fabrics (BWKF) with reinforcing yarns in the warp and weft direction to improve its mechanical behavior. In this work, the possibilities of the knitting technique are investigated, and a finite element model for comparing different variants is developed and validated. A meso-scale Finite-Element-Method (FEM) model of the BWKF is used. The simulation results with the meso-scale model show a good correlation with experimental data by a description of bending strength and stiffness of different FRP configuration variations. The model can be used in further investigation of fiber-reinforced polymer (FRP) made from BWKF. Full article

Chitosan (CTS) has been used as a nerve guidance conduit (NGC) material for bridging peripheral nerve defects due to its biocompatible, biodegradable, and non-toxic properties. However, the nerve regeneration effect of chitosan alone is restricted due to its inadequate biological activity. Herein, a composite, bioactive chitosan based nerve conduit, consisting of outer warp-knitted tube scaffold made from medical-grade chitosan fiber, and inner porous cross linked carboxymethyl chitosan (C-CM-CTS) sponge with radial texture was developed. The inner wall of the scaffold was coated with C-CM-CTS solution. CM-CTS provided favorable bioactivities in the composite chitosan-based nerve conduit. An in vitro study of CM-CTS revealed its satisfying biocompatibility with fibroblast and its inhibition of oxidative damage to Schwann cells. As the internal filler of the NGC, the lyophilized sponge of C-CM-CTS showed a longitudinal guidance effect for nerve reconstruction. After 10 mm defect in rat sciatic nerve was bridged with the composite bioactive chitosan-based nerve conduit, the nerve conduit was able to effectively promote axonal regeneration and played a positive role in inducing nerve regeneration and functional recovery. In addition to the functional advantages, which are equal to those of an autograft; the technology for the preparation of this conduit can be put into mass production. Full article

Lightweight structures with high energy absorption capacity are in high demand for energy absorption applications in a variety of engineering fields, such as aerospace, automotive, and marine engineering. Anti-impact composites are made of energy-absorbing materials that are incorporated into structures to protect the occupant or sensitive components against strikes or falls. This study deals with an experimental investigation of multi-layer composites consisting of cork and warp-knitted spacer fabrics (WKSF) for anti-impact applications. Composites were designed and created with a laser cutting machine in eight different configurations. To measure the energy absorption of the manufactured composite samples, a low-velocity drop-tower machine was designed, and the maximum reaction force due to the strike of the impactor on the specimens was measured by a dynamometer located under the samples. Moreover, energy absorption and specific energy absorption capacities were calculated for each specimen. In the final part of this study, the Life Cycle Assessment (LCA) of the designed composites was calculated to understand the eco-friendly properties of the composites. Full article

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. Full article

The load-bearing function of articular cartilage tissue contrasts with the poor load-bearing capacity of most soft hydrogels used for its regeneration. The present study explores whether a hydrogel based on the methacrylated natural polymers chondroitin sulfate (CSMA) and hyaluronic acid (HAMA), injected into warp-knitted spacer fabrics, could be used to create a biomimetic construct with cartilage-like mechanical properties. The swelling ratio of the combined CSMA/HAMA hydrogels in the first 20 days was higher for hydrogels with a higher CSMA concentration, and these hydrogels also degraded quicker, whereas those with a 1.33 wt% of HAMA were stable for more than 120 days. When confined by a polyamide 6 (PA6) spacer fabric, the volumetric swelling of the combined CSMA/HAMA gels (10 wt%, 6.5 × CSMA:HAMA ratio) was reduced by ~53%. Both the apparent peak and the equilibrium modulus significantly increased in the PA6-restricted constructs compared to the free-swelling hydrogels after 28 days of swelling, and no significant differences in the moduli and time constant compared to native bovine cartilage were observed. Moreover, the cell viability in the CSMA/HAMA PA6 constructs was comparable to that in gelatin–methacrylamide (GelMA) PA6 constructs at one day after polymerization. These results suggest that using a HydroSpacer construct with an extracellular matrix (ECM)-like biopolymer-based hydrogel is a promising approach for mimicking the load-bearing properties of native cartilage. Full article

As an aspect of intelligent clothing, e-textile sensors can flexibly sense and transmit information about human bodies and environments. However, difficulties relating to their technology and the variation in textile materials employed in their manufacture still limit their ability to analyze and be applied. The authors’ previous publication deployed a pressure sensor with warp-knitted spacer fabrics, wet-knitted fabrics, Ag-yarns, and Fe-yarns. An equivalent circuit analyzed the resistance behavior with some effects of the Ag-coated twisted yarns. In the present paper, the authors continue to evaluate the correlation model R-ε and the effects of the Fe staple-fiber spun yarns in detail. Together, the two studies provide an extensive understanding of the textile-related elements that affect pressure sensors. In addition, the process and the analysis (correlation model) could bring the textile sensors here developed close to the manufacturing stage, particularly for high precision/adjustable applications. We also develop a simple touch sensor matrix to demonstrate the potential of the sensor and the analyzing method. Full article