Optimization of electromagnetic shielding of three-dimensional orthogonal woven hybrid fabrics in ku band frequency region by response surface methodology

Electromagnetic shielding (EMS) has become the necessity of the present era due to enormous expansion in electronic devices accountable to emit electromagnetic radiation. The principal target of this paper is to originate three-dimensional (3D) orthogonal fabrics with conductive hybrid weft yarn and to determine their electromagnetic shielding. DREF-III core-spun yarn using copper filament in the core and polyphenylene sulfide (PPS) fiber on the sheath and fabric constructed of such yarn has a promising electromagnetic shielding characteristic. Box–Behnken experimental design has been employed to prepare various samples to investigate the electromagnetic shielding efficiency of 3D orthogonal woven structures. The orthogonal fabric samples were tested in an electromagnetic Ku frequency band using free space measurement system (FSMS) to estimate absorbance, reflectance, transmittance, and electromagnetic shielding. The increase in copper core filament diameter and hybrid yarn linear density enhances the EMS of orthogonal fabric. Statistical analysis has been done to bring out the effect and interaction of various yarn and fabric variables on EMS. Metal filament diameter, orientation, sheath fibers percentage, and fabric constructional parameters significantly affected electromagnetic shielding efficiency. The inferences of this study can be applied in other 3D structures like angle interlock, spacer fabrics for curtains, and coverings for civilians and military applications.

Development of Airlaid Non-Woven Panels for Building’s Thermal Insulation

As the need to ensure thermal comfort in buildings is constantly evolving, new technologies continue to emerge with the aim to develop efficient thermal insulation materials. This study aims to explore a textile technology using Airlaid process to develop non-woven fabrics made of natural fibers extracted from Posidonia Oceanica’s waste for assessing their suitability for insulation products in construction field. This technology offers the feature to develop isotropic non-woven structures by orienting randomly the fibers on the fabric surface. The web composed of a mixture of Posidonia Oceanica fibers and a proportion of thermoplastic fibers is then thermally bonded in an oven followed by cooling in order to ensure the solidification of the bonding areas. The prepared panels are then analyzed for the thermal conductivity. It was found that their thermal conductivity is close to commonly used thermal insulation materials, ranging between 0.03515 W/m.K and 0.03957 W/m.K, which allows the non-woven panels to compete with widely-used insulation materials for building’s field. The second part of this work aims to determinate the Posidonia panel's resistance to five common mold types in buildings (Aspergillus niger, Penicilumfuniculosum, Trichoderma viride, Chaetomium globosum, Paecilomycesvariotii). In fact, at high moisture content, molds are likely to develop on cellulosic materials affecting indoor air quality and eventually causing a variety of health risks to occupants. However, optic microscope results showed no growth of molds on the Posidonia samples which allows conceiving reliable thermal insulation materials.

Modelling of Auxetic Woven Structures for Composite Reinforcement

The current research is focused on the design and development of auxetic woven structures. Finite element analysis based on computational modeling and prediction of axial strain as well as Poisson’s ratio was carried out. Further, an analytical model was used to calculate the same parameters by a foldable zig-zag geometry. In the analytical model, Poisson’s ratio is based on the crimp percentage, bending modulus, yarn spacing, and coefficient of friction. In this yarn, properties and fabric parameters were also considered. Experimental samples were evaluated for the actual performance of the defined auxetic material. Auxetic fabric was developed with foldable strips created in a zig-zag way in the vertical (warp) direction. It is based on the principle that when the fabric is stretched, the unfolding of the folds takes place, leading to an increase in transverse dimensions. Both the analytical and computational models gave close predictions to the experimental results. The fabric with foldable strips created in a zig-zag way in the vertical (warp) direction produced negative Poisson’s ratio (NPR), up to 8.7% of axial strain, and a maximum Poisson’s ratio of −0.41 produced at an axial strain of around 1%. The error percentage in the analytical model was 37.14% for the experimental results. The computational results also predict the Poisson’s ratio with an error percentage of 22.26%. Such predictions are useful for estimating the performance of auxetic woven structures in composite reinforcement. The auxetic structure exhibits remarkable stress-strain behavior in the longitudinal as well as transverse directions. This performance is useful for energy absorption in composite reinforcement.

ANALYSIS OF THE PHYSICO-MECHANICAL PROPERTIES OF DIFFERENT WOVEN STRUCTURES WITH POTENTIAL APPLICATIONS IN THE HEALTHCARE AND HYGIENE SECTO

This study aimed at creating different woven textile fabrics with potential applications related to healthcare and hygiene by using textile yarns obtained from diverse fibre blends and by varying the structural parameters of the fabrics. Four different weave patterns were used to create the fabrics: warp rib, 2/2 twill, 2/2-pointed twill and hopsack. Cotton fibres were mostly used, but fibres made from regenerated cellulose with extra antibacterial properties (silver ions) and from ultra-high tenacity polyethylene (UHMWPE) were also used in different proportions. The choice and combination of these types of yarns, along with the rational design for making the fabrics contribute to supporting the sustainability of the textile field, improving the quality of life of people, especially those with special needs (the elderly, people with disabilities, or people with various diseases that limit their free movement) and also ensuring a longer usage time and manifestation of functionalities. A comparative analysis regarding the influence of structural parameters, but also the influence of fibre types on the physico-mechanical performance of the created fabrics was made.

Recent Advances in Fiber-Shaped Electronic Devices for Wearable Applications

Fiber electronics is a key research area for realizing wearable microelectronic devices. Significant progress has been made in recent years in developing the geometry and composition of electronic fibers. In this review, we present that recent progress in the architecture and electrical properties of electronic fibers, including their fabrication methods. We intensively investigate the structural designs of fiber-shaped devices: coaxial, twisted, three-dimensional layer-by-layer, and woven structures. In addition, we introduce remarkable applications of fiber-shaped devices for energy harvesting/storage, sensing, and light-emitting devices. Electronic fibers offer high potential for use in next-generation electronics, such as electronic textiles and smart integrated textile systems, which require excellent deformability and high operational reliability.

Piezo-Resistive Properties of Bio-Based Sensor Yarn Made with Sisal Fibre

In this work, a sensor yarn based on a natural sisal yarn containing a non-electro-conductive core impregnated with PVA polymer and coated by PEDOT:PSS polymer as an electro-conductive sheath was investigated. The main objectives include the development of this new sensor yarn as a first step. Then, we look towards the insertion of this sensor yarn into different woven structures followed by the monitoring of the mechanical behaviour of composite materials made with these fibrous reinforcements. The combined effect of the structural geometry and the number of PEDOT:PSS coating layers on the properties of the sensor yarns was investigated. It was found that the number of PEDOT:PSS coating layers could strongly influence the electromechanical behaviours of the sensor yarns. Different methods of characterization were employed on strain-sensor yarns with two and four coating layers of PEDOT:PSS. The piezo-resistive strain-sensor properties of these selected coating layers were evaluated. Cyclic stretching-releasing tests were also performed to investigate the dynamic strain-sensing behavior. The obtained results indicated that gauge factor values can be extracted in three strain regions for two and four coating layers, respectively. Moreover, these strain-sensor yarns showed accurate and stable sensor responses under cyclic conditions. Furthers works are in progress to investigate the mechanism behind these first results of these sisal fibre-based sensors.

Investigating the Performance of Sewn Seams from Woven Fabrics

Seam performance ensures the durability, attractiveness, strength etc. of the sewn garments. Fabric types, fabric densities, fabric strength, seam types, sewing thread count, thread strength, stitch densities and stitch types influence the performance of a sewn seam. This paper investigates the performance of sewn seam of various structure of woven fabric. The variables of this research are stitch densities (SPI), sewing thread count, seam types and woven structures. We conduct our research over plain, twill 2/1, twill 2/2, oxford and poplin woven structure. Firstly, we apply lockstitch (301) to produce superimposed, lapped and bound seam on the woven sample by using thread count 27 Tex, 30 Tex, 20/2 Tex, 40 Tex, 40/2 Tex, 40/3 Tex having stitch densities (SPI) 8, 10 and 12. Then according to ASTM D1683 standard, we measured the tensile strength test and recorded the seam breaking strength (N). We apply error bars over each diagram to investigate the standard deviation. Finally, we discuss four hypothesis to conclude our research work. We found higher seam breaking strength with the increase of thread count and SPI. The bound seam samples has shown superior seam breaking strength than superimposed and lapped seam; poplin structure surpassed to others. The seam efficiency of the samples varies from 60–90% and do not exceeds 100%. Finally, we found some significant alternatives hypothesis of the population since F values exceeded F critical values for the sewn seam.

Effect of Parameters on the Runoff Erosion Control Performance of Structurally Modified Jute and Coir Geomeshes over Loamy Sand

Soil erosion is a serious environmental problem that can be controlled using bioengineering techniques. In using a bioengineering technique, temporary reinforcement is performed with geomeshes until vegetation takes root. In this study, structurally modified jute and coir geomeshes were tested for runoff erosion control and runoff volume over loamy sand at different slope angles. The laboratory results revealed that all parameters (slope angle, type of weave and type of material) had a significant effect on the erosion control performance of geomeshes. The slope angle contributed most (52.34%) to runoff erosion control, followed by weave type (25.79%) and type of material (12.28%). At lower and medium slope angles (of 15o and 30o, respectively) the twill-woven structure of coir geomeshes provided better erosion control than plain- and satin-woven structures, while plain-woven jute geomeshes demonstrated better erosion control at all slope angles. To understand the overall impact, a germination test was also conducted. According to the germination test results, the twill weave of jute geomeshes provided the highest rooting length. In general, plain-woven jute geomeshes are preferred for better erosion control on a high slope angle, while plain and twill can be used on a low slope angle.