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.

Electromagnetic shielding performance of copper and silver-plated hybrid yarn based multilayer fabrics in C & X band frequency range

In the present study, a strategic designing of multilayer shield was planned to enhance the multiple reflection phenomenon to achieve maximum absorption properties in microwave frequency (C & X band) range. Multi-layer EMR shields were developed using pure cotton fabric and conductive woven fabrics, incorporated with copper- based & silver-plated hybrid yarn. First of all, single layer fabrics were produced in five variants, nomenclature as L1A (pure cotton) L1B, L1C (copper-based hybrid yarn), LS1B and LS1C (silver plated hybrid yarn). These five variants were used to prepare four sets of double & triple layer fabric. In both double and triple layer composition, L1A fabric (pure cotton) was used as top layer followed by B and C series fabrics, containing copper and silver-plated hybrid yarn. The EMSE performance in C and X band frequency range of single layer, double layer and triple layers in terms of scattering parameters S11(reflectance) & S21 (transmittance) in vertical and horizontal wave polarization was studied. It was found that number of layers, layer composition, orientation of metallic yarn, frequency and EM wave polarization have significant influence on overall electromagnetic shielding effectiveness.

Tekstil Takviyeli Beton Üretiminde Kullanılmak Üzere Yüksek Performanslı Hibrit İplik Geliştirilmesi Ve Üretim Parametrelerinin Optimizasyonu

Textile-Reinforced Concrete (TRC) is a new construction material and has been used in civil engineering applications such as façade systems, sandwich panel and outside furniture during the past several decades. Generally in TRC, glass, carbon filaments, etc. are used to reinforce concrete because these high-performance filaments have superior mechanical properties and corrosion resistance. Coating of these filaments with different polymers provide extra performance for TRC’s durability. But, because of coating materials’ cost and stiffness, using of coating for TRC is not so advantageous. For these reasons, new approaches are needed. In this study, a new hybrid yarn design and production for TRC are emphasized. AR-Glass and polypropylene filament were used for production of hybrid yarn by commingling method. It was aimed to optimize the parameters of commingling yarn production with Taguchi orthogonal design. The experiments were performed by using L9 orthogonal matrix with respect to Taguchi approach. The best strength value in the study was obtained in production parameters where the machine production speed is 50 m / min, the air pressure is 6 bar and the feeding amount is 2%. Analysis of variance (ANOVA) and signal/noise ratio were used to evaluate the experiment results. As a result of the analysis, it has been observed that the machine production speed has the greatest effect on the breaking strength and the feed amount has the lowest effect.

Characterization and Numerical Modelling of Through-Thickness Metallic-Pin-Reinforced Fibre/Thermoplastic Composites under Bending Loading

Through-Thickness Reinforcement (TTR) technologies are well suited to improving the mechanical properties in the out-of-plane direction of fibre-reinforced composites. However, besides the enhancement of delamination resistance and thus the prevention of overall catastrophic failure, the presence of additional reinforcement elements in the composite structure affects also the mechanical properties in in-plane direction. In this work, the flexural behaviour of a glass-polypropylene (GF/PP) hybrid yarn-based composite with TTR in form of metallic pins has been investigated experimentally and numerically. The insertion of the metallic pins is realized via thermoactivated pinning technology (TAP). In four-point-bending tests, it is shown that the flexural stiffness and strength decreases with an increase of the overall pin density. Hereby, it is observed that the pins act as crack initiators. For numerical modelling on specimen level, a continuum damage mechanic (CDM) model is used to predict the nonlinear deformation response of the composite, as well as fibre fracture and matrix cracking. A debonding and slipping phenomena of the pin in the composite is modelled by a cohesive zone modelling approach for the interface between pin and composite.

Effects of Micro-Braiding and Co-Wrapping Techniques on Characteristics of Flax/Polypropylene-Based Hybrid Yarn: A Comparative Study

Micro-braiding and co-wrapping techniques have been developed over a few decades and have made important contributions to biocomposites development. In this present study, a set of flax/polypropylene (PP) micro-braided and co-wrapped yarns was developed by varying different PP parameters (PP braiding angles and PP wrapping turns, respectively) to get different flax/PP mass ratios. The effects on textile and mechanical characteristics were studied thoroughly at the yarn scale, both dry- and thermo-state tensile tests were carried out, and tensile properties were compared before and after the braiding process to study the braidabilities. It was observed that PP braiding angles of micro-braided yarn influenced the frictional damage on surface treatment agent of flax roving, the cohesive effect between PP filaments/flax roving, and the PP cover factor; PP wrapping turns of co-wrapped yarn had a strong impact on the flax roving damage and the PP coverage, which further influenced the characteristics. Micro-braided yarn and co-wrapped yarn with the same flax/PP mass ratio were compared to evaluate the two different hybrid yarn production techniques; it was proven that micro-braided yarn presented better performance.

Characterization of the electrical behavior of a discontinuous hybrid yarn textile made of recycled carbon and PA6 fibers during Joule heating

The Joule heating of carbon fiber-based textiles enables an energy- and cost-efficient processing of carbon fiber reinforced thermoplastic parts. This article introduces a new method to pass direct current into a dry, not pre-consolidated hybrid yarn textile based on recycled carbon fibers and polyamide 6 fibers. The aim is to melt polyamide fibers, subsequently impregnate carbon fibers, and finally consolidate the material to form a composite part in a single process step. To increase the reliability of this technology, the electrical properties and the behavior of the material during the heating process must be thoroughly investigated. It will be addressed how the material is characterized during the process and how the changing resistivity of the textile affects the current flow between the electrodes to generate intrinsic heat. Moreover, a method to determine the effective material resistivity by finite element simulation on the fiber scale based on a CT scan is presented. Thus, a validated material model with respect to the temperature development in the textile based on ρ = ρ (Τ) was established.

Influence of matrix systems on the deformation behavior of adaptive fiber-reinforced plastics

Adaptive structures contain actuators that enable the controlled modification of system states and characteristics. Furthermore, their geometric configuration as well as physical properties can be varied purposefully. The geometric configuration of adaptive fiber-reinforced plastics can be changed by varying the bending modulus of the matrix material. Hence, this research work presents the influence of thermosetting matrix material with different bending moduli on the deformation behavior of adaptive fiber-reinforced plastics. Firstly, shape memory alloys were converted into shape memory alloy hybrid yarn in order to realize this goal. Subsequently, shape memory alloy hybrid yarn was textile-technically integrated into reinforcing fabrics by means of weaving technology. The bending modulus of the thermosetting matrix material was changed by mixing modifier into it. The Seemann Corporation Resin Infusion Molding Process was used for infusion. Later, the deformation behavior of adaptive fiber-reinforced plastics was characterized. Results revealed that the maximum deformations of adaptive fiber-reinforced plastics with resin and modifier at a mixing ratio of 9:1 and 8:2 were increased to 34% and 63%, respectively, compared to adaptive fiber-reinforced plastics infiltrated by the reference resin. The maximum deformation speed during heating and cooling of adaptive fiber-reinforced plastic with the mixing ratio of resin and modifier at a value of 8:2 were 41.17 mm/s and 26.89 mm/s, respectively.