Warp Direction Research Articles

LOAD-BEARING BEHAVIOR OF SHORT-FIBER-REINFORCED TEXTILE CONCRETE FOR A WRAPPING PROCESS

In the research project WiFaPu (Wrapping Process for highly fiber-reinforced concrete using the example of a pump sump), a new manufacturing process for components made of Short-Fiber-Reinforced Textile Concrete is being developed. Wrapping concrete continuously around a formwork places high-level requirements on concrete and reinforcement properties. This paper presents the investigations on the load-bearing behavior of wrappable Short-Fiber-Reinforced Textile Concrete with uncoated textile reinforcement made of AR-glass in tensile tests. The placing of the concrete into the wrapped layers by casting, laminating or spraying as well as the short fiber content and warp/weft direction of the uncoated fabric have major influence on the load-bearing behavior of the tested specimens. Members produced in a spraying or laminating process showed low ultimate fabric stresses and unsatisfactory crack pattern in warp direction of the fabric due to the lacing of rovings leading to lower matrix penetration. Casting of specimens lead to significantly higher textile fracture stresses if textile fabrics are slightly tightened while installing in the formwork. Also vibrating the fine-grained concrete leads to better roving penetration compared to the spraying process. The addition of short fibers partially compensates negative effects of the textile weave in the warp direction.

Electrical conductivities and temperature distributions of carbon fiber 3D woven composites with different electric field direction

Electrical conductivities and temperature generations are related closely for carbon fiber composites under electric fields. Here we reported the current conductivity and electro-thermal behavior of carbon fiber reinforced 3D orthogonal woven structure composites (3DOWCs) along different current directions. The influence of woven architectures and contacts on electrical and thermal behaviors was analyzed with finite element analysis (FEA) model. We found that the conductivity was the highest along warp direction and the lowest along Z-binder direction. The conductivity increased with the increase of in-plane angles. The overall conductivity of Z-binder direction was affected by weft/Z-binder yarn interface. In-plane angle directions, the warp/weft interfacial conductivity affected overall conductivities, which had the largest temperature contribution. The maximum current density and temperature of warp yarns decreased with the increase of in-plane angles. The proportion of weft yarns in current density and temperature rise increased with the increase of in-plane angles.

Comparative study of tensile behavior in micro/nanofiber-enhanced epoxy nanocomposites featuring different textile structures

Recent advancements in nanofiber production technology have opened up exciting possibilities for highly sophisticated applications in nanofiber-based structures, particularly in the realm of nanofiber yarns. These yarns serve as fundamental components in various fabric designs, encompassing woven, knitted, braided, and nonwoven patterns. Additionally, these fabrics can serve as reinforcement in nanocomposites with a polymeric matrix. This study aims to investigate the reinforcing effect of micro/nanofibers in various fabric structures, such as nonwoven, woven, and knitted fabrics. Apart from depositing micro/nanofibers, we successfully manufactured a micro/nanofiber yarn made of polyamide-6. This was achieved by employing two nozzles equipped with opposite charges and flat-tipped needles. Furthermore, we created both woven and weft-knitted fabrics using this micro/nanofiber yarn. Subsequently, we utilized nonwoven, woven, and weft-knitted fabrics to reinforce epoxy resin. The results indicated that the nanocomposite reinforced with woven fabric in the warp direction, featuring a volume fraction of 12%, exhibited the highest Young’s modulus (7500 MPa, 5.47 times more compared to epoxy) and ultimate strength (112 MPa, 5.09 times more compared to epoxy). This study represents a pioneering step towards the development of nanofiber-based reinforcements with promising potential applications.

A COMPARISON OF THE THREE TECHNIQUES IN PREDICTING BREAKING STRENGTH OF COTTON AND BLENDED WOVEN FABRICS

With the development of technology, artificial intelligence applications in the textile industry are increasing. The uses of these methods present very good results in cases where statistical methods are lacking in the accurate evaluation and analysis of the past data of the enterprises and the estimation of their future situations. In this study, some models are developed, based on this relationship, to estimate the breaking strength of cotton woven fabrics and polyester/viscose blended woven fabrics separately. Breaking strength is considered one of the most important performance characteristics of woven fabrics. It is mostly determined by the structural elements of the fabric. Multiple linear regression, artificial neural networks and random forest algorithms are employed to perform statistical and stochastic analyses on these elements by using industrial data. A total of 147 fabric data sets in warp and weft directions were used for training and test data in cotton fabrics, and 53 fabric data sets in warp and weft directions in blended fabrics. Appropriate models are generated by using Minitab Statistics and Matlab software. Yarn linear densities, yarn production methods, twist amounts, fabric densities, crimp ratios, unit area weights, various weave factors and fabric structure factors were selected as variables of the models estimating the breaking strength of fabrics in both warp and weft directions. These factors were included in the models separately, and the subset that gave the best results was selected and the models were revised. For the three models created, it was seen that the regression models and models based on artificial neural networks performed well in both cotton fabrics and blended fabrics, while random forest algorithms were not very accurate in estimating the breaking strength.

Fabric handling evaluation of woven shirting fabrics by the fabric touch tester

A fabric touch tester is a novel instrument with fabric handling properties. Its principal advantage is that the device has integrated modules for compression, surface friction, and thermal and bending properties. This module integration simplifies the testing process, and provides an efficient measurement method, and a comprehensive physical index. This study focused on woven fabrics for dress shirts. The fabric samples comprised three groups with various yarn compositions – that is, cotton, polyester, and wool. Sample group 1 was composed of cotton, polyester, and blended yarns; sample group 2 mainly compared the effect of twist yarns on the fabric touch; and sample group 3 was composed of wool and blended yarns with polyester. The handling properties were assessed by compression work and the compression recovery rate for the compression attributes. The results revealed that fabric (T100p1) with high twist-level yarns had a higher value of compression work (242.56 gf*mm2), and the texture type may affect the compression characteristics more significantly than the blending ratio. The fabric touch tester can also distinguish small changes in the compression properties of samples (0.43–0.71), the maximum heat flux and surface roughness amplitude for the thermal and surface roughness properties. The results revealed that the maximum heat flux value of all the samples in this study was 1109 Wm−2, the sample C100 using pure cotton yarn had the highest maximum heat flux value (1270 Wm−2). Moreover, the sample W100 with 100% wool fiber yarn had the highest surface roughness amplitude in the warp direction (81 μm) and surface roughness amplitude in the weft direction (67 μm). Finally, the bending average rigidity was used to assess the bending performance of the fabric samples. These fabric touch tester indicators were applied to analyze the fabric handling characteristics of woven shirting fabrics, and perform cross-analysis among samples.

Process optimization and performance verification of CFRP laser surface modification

AbstractAdhesive bonding has gradually replaced mechanical connections as the primary method for composite material bonding, with surface quality being the key factor determining the effectiveness of composite material adhesion. Laser surface treatment, known for its green and precise characteristics, has garnered widespread attention from both academia and industry. However, the process parameters of laser surface treatment are complex, efficiency is low, and the mechanism remains unclear. This paper, based on the response surface methodology (RSM), investigates the influence of laser secondary parameters on the resin removal rate of carbon fiber reinforced polymer/plastic (CFRP) surfaces and the impact of defocusing on surface treatment efficiency. The results indicate that when the total laser energy density (Et) is 69 J/cm2, the overlap ratio in the warp direction (OLs) is 76%, and the overlap ratio in the weft direction (OLh) is 85%, the surface tensile shear strength increases by 90.59% and 27.77% compared to the original surface and polished surface, respectively. When the defocus distance is +8 mm, the efficiency of laser surface treatment is 2.25 times that of non‐defocus, with minimal impact on mechanical performance. The surface treatment mechanism, with changes in Et, primarily involves the pure thermal decomposition of the resin matrix in an oxygen‐free environment, oxidative decomposition, and the synergistic action of the decomposition products' oxidation. Through the coupled optimization of laser process parameters, this work enhances the efficiency and effectiveness of composite material adhesive surface treatment, promoting the engineering application of laser technology.Highlights By establishing a response surface model, the study elucidated the impact patterns of laser secondary parameters (overlap rates in the warp and weft directions, total energy density) on the resin removal rate of CFRP surfaces. Based on the laser surface treatment phenomena at different total energy densities, the study analyzed and revealed the mechanism of near‐infrared (1064 nm) laser resin removal from CFRP surfaces. By increasing the spot size through defocusing, the efficiency of laser surface treatment was enhanced, and the impact on the interfacial properties of CFRP after defocused treatment was validated.

On the strain-rate dependent compressive failure behavior of 2.5D woven composites

Understanding the mechanical failure behavior of 2.5D woven composites (2.5DWC) is challenging due to their complex fabric configurations and multi-scale structural properties. This challenge is particularly prominent in the realm of dynamic mechanical properties and damage failure mechanisms under high strain rates. Therefore, a comprehensive approach combining a series of quasi-static and dynamic mechanical tests with mesoscale finite element simulation methods is adopted to perform an in-depth analysis of the mechanical response and progressive damage behaviors of a Twilled 2.5D Woven Composite (T-2.5DWC) under different strain rate loads. The results indicate that the compressive strengths as well as the failure behaviors of the T-2.5DWC exhibit an obvious strain rate strengthening effect in both the weft and warp directions. In addition, the rate-dependent finite element model developed in this study accurately simulates the compressive modulus and strength of T-2.5DWC along both the warp and weft directions under various strain rates.

Influence of the mesostructure on the fatigue behaviour of textile composites

The aim of the present work is to analyze the influence of the mesostructure on the fatigue behaviour of textile composites. By affecting the stress distribution within a laminate, the mesostructure largely determines the damage evolution under cyclic loadings. In this work, plain woven fabrics with different number of layers were tested under cyclic loadings along the warp and weft directions, monitoring the damage evolution. The differences in meso- and micro-structure, together with the position of the bundle in the laminate, affect the fatigue-induced damage mechanisms. The stress fields obtained from 3D Finite Element analyses shed light onto the influence of the mesostructure on the damage onset. Eventually, a stress-based strategy to predict the life to crack initiation is proposed and validated against experimental data.

Flexural strengthening of RC beams by advanced concrete canvas

AbstractIn this study, concrete canvas (CC) layers were used as a novel method to strengthen reinforced concrete (RC) beams because of their flexibility, rapid installation, fast curing, and rapid strengthening. Due to the importance of the CC mechanical properties, various combinations of cement including ordinary (OPC) and High Alumina (HAC), as well as silica fume, were investigated to determine the optimal mixture for strengthening RC beams. The results indicate that substituting 75% of HAC with OPC significantly boosted flexural strength by 33%, and increased tensile strength in the warp and weft directions by 25% and 21%, respectively. The study examined six RC beam specimens in a four‐point flexural test, assessing their flexural properties, ductility, cracking behavior, and energy dissipation. The number of CC layers and the bonding method, which involved either the conventional externally bonded reinforcement (EBR) technique or the externally bonded reinforcement on grooves (EBROG) technique were studied. The experimental results revealed the superiority of the EBR method over the EBROG technique due to the uniform bond between CC and the concrete surface. Using the EBR technique, improvements of 35% and 51% were observed in the load‐carrying capacity of the beams strengthened with one and two CC layers, respectively. It is while for the beam with an improved loading capacity of 51%, the crack width decreased from 5.3 to 2.1 mm, and the energy dissipation increased by three times compared to the control specimen. Theoretical analysis also was performed to calculate the load‐carrying capacity of the RC beams strengthened with CC layers.

Static and dynamic mechanical behavior of intra‐hybrid jute/sisal‐reinforced polypropylene composites: Effect of stacking sequence

AbstractIn the current research investigation, jute and sisal intra‐hybrid woven fabric were specifically tailored to maintain jute and sisal in weft and warp directions, respectively. Jute sisal intra‐hybrid composites were prepared with four layers of intra‐hybrid woven fibers using a compression molding technique. Physical, mechanical (static and dynamic), and thermal stability behavior were investigated, and their structure–property relationship has been established. The obtained results showed that jute‐sisal cross‐interplay‐based hybrid composites recorded maximum tensile and flexural modulus values with minimum anisotropy. It can be concluded from the current experimental investigation that weft/warp orientation and stacking sequence play a significant role in defining the mechanical performance and anisotropic nature of woven fiber‐reinforced laminated composites. Also, the anisotropic properties can be minimized by investigating the effect of fiber orientation and hybridization of natural fibers‐based laminated composites.Highlights Woven mats were tailored to orient different fibers in warp and weft directions. The influence of the fiber's orientation and stacking sequence was analyzed. Fiber orientation and hybridization have influenced mechanical performance. The alternative stacking sequence has shown the highest mechanical properties.

Union Dyeing of Cotton-Silk Blended Woven Fabric Using Tanin Bio-mordant and Thyme as a Colourant

The study explores the application of tea leaf-extracted tannin as a bio-mordant and thyme extract as a natural dye on cationized silk-cotton blend fabric to enhance colour fastness and absorption. The colour strength and depth (shown as DL, Da, and Db values) on silk-cotton blend fabric were investigated in the CIE lab test. The results showed that temperature, shade percentage, and mordanting had a substantial impact on the dyeing process efficacy at DL = 30.61, Da = 11.49 and Db = 12.77. When the temperature was raised to 90 °C and the dye content was increased to 120%, the dyed sample's colour fastness (as measured by wash, rubbing, and perspiration) significantly improved, acquiring a grade of 4 to 5, which indicates good to excellent. There was a slight change in wet rubbing fastness from grade 3 to grade 4, indicating good to fair. The K/S values of the silk and cotton fibres, which ranged from 8.89 to 7.94 on average, respectively, demonstrated that the processes of bio-mordanting and cationization enhanced the absorption of dye. Tensile strength and extension increased in the weft direction to 22.19 N force and 5.21% extension at break, while the warp direction showed a fall to 6.63 N force and a rise in extension of 0.72%. FTIR spectroscopy confirmed the presence of Amino (N-H) bonds, Carbohydrate bonds (CH), Tannins, and Terpenoid phytochemicals of thyme in the dyed sample. The study highlights the potential of thyme extract as a natural dye and its benefits in improving the dyeing properties of silk-cotton blend fabric.

Relation between water absorption and mechanical properties of flax 3D braided yarn woven fabric PLA bio-degradable composites

Natural fibre (flax) plain type of woven fabric is developed by using solid braided yarn and is utilised as filler material and PLA (polylactic acid) as a matrix. Solution casting is then used to create sheets of pure PLA and flax fabric–PLA. Composites are manufactured by sheets sequencing technique using the hot compression moulding method. Water absorption, thickness swelling and flexural tests are performed in loading directions of warp and weft of the composites. Results revealed that the absorption of water and swelling of thickness are enriched with an addition of flax fabric. The weft direction loaded composite displayed greater values of water uptake and thickness swelling. The warp direction loaded composites demonstrated the highest flexural strength (92.3 MPa) and modulus (4.5 GPa) compared to weft direction loaded composites. These values are decreased after water absorption.

The model of ring-spun slub yarn based on random fiber arrangement and its application: Part 2 Prediction of morphology parameters for slub yarn and simulation of slub fabric

The morphology parameters of slub yarn include slub length, base length, the length of the transitional segment, slub multiple, slub linear density, base linear density, and average linear density of slub yarn. These parameters have an impact on the appearance of both slub yarn and its fabric. This paper aims to predict the morphology parameters of spun slub yarn by utilizing the model proposed in Part 1 for ring-spun slub yarns. Once the slub generation mode was known, slub yarn could be simulated with the morphology parameters. The simulated slub fabric was obtained by arranging the simulated slub yarn in the warp and weft directions. According to our study, the prediction accuracy of each morphology parameter was over 80% by comparing the simulated parameters with the measured ones of spun slub yarn. The CV (coefficient of variation) of the slub segment number per unit area was utilized to assess the distribution of slubs in the simulated fabric. This research can facilitate the development of slub yarn and its fabric, providing guidance for technicians to enhance production technology.

Low-Velocity Impact and Post-Impact Residual Flexural Properties of Kevlar/EP Three-Dimensional Angle-Interlock Composites.

In this study, five three-dimensional angle-interlock fabrics with different warp and weft densities were fabricated using 1000D Kevlar filaments. The Kevlar/EP composites were prepared by vacuum-assisted molding techniques. The low-velocity impact property of the composite was tested, focusing on the effects of the warp and weft densities, impact energy, impactor shape, and impactor diameter. The damage area, dent depth, and crack lengths in the warp and weft direction were used to evaluate the impact performance, and the specimens were compared with plain-weave composites with similar areal densities. The dominant failure mode of the conical impactor was fiber fracture, while the dominant failure mode of the hemispherical impactor was fiber-resin debonding. The cylindrical impactor showed only minor resin fragmentation. The residual flexural strength of the composite after impact was tested to provide insights into its mechanical properties. The study findings will provide a theoretical basis for the optimization of the design of impact-resistant structures using such materials and facilitate their engineering applications.

Investigating the Effect of Elastane Use on Tailorability and Appearance of Wool and Wool Blend Suiting Fabrics

ABSTRACT In this study, the effect of the use of elastane on the tailorability and appearance of 100% wool and different proportions of wool – man-made fiber blended worsted suiting fabrics was investigated. The evaluations were made by means of mechanical properties. Although the amount of elastane used in the weft yarn of elastane-containing fabrics differed in each group, it was observed that the effect of elastane varied mainly depending on the fabric weight. It was seen that the use of elastane increased the bending rigidity for heavy weight (290 g/m2 and above) fabric groups (groups 1 and 6) and negatively affected tailorability due to low shear rigidity for fabrics other than these groups. Except for the group with low fabric weight, all groups were found to improve the appearance in both weft and warp directions. However, it was concluded that fabrics containing 7% or more elastane in the weft may have a seam puckering problem due to low formability in the warp direction. The effect of elastane on extensibility was found to be influenced by fabric density, elastane content and construction in addition to fabric weight. The low fabric density and weight caused excessive extensibility, resulting in very poor tailorability.

Mechanical Property Characterization of Architectural Coated Woven Fabrics Subjected to Freeze–Thaw Cycles

This paper presents experimental investigations into the freeze–thaw response of two common architectural coated woven fabrics. Strip specimens for the tensile tests were exposed to −20 °C for three hours followed by three hours of thaw at ambient temperatures. This was repeated for a maximum of 100 cycles. Afterwards, the residual tensile strength was measured and compared to results achieved for test specimens without prior freeze–thaw cycles. Maximum mean tensile strength reductions of approximately 21% (warp direction) and 19% (weft direction) for probed polytetrafluoroethylene (PTFE)-coated woven glass fiber fabrics were identified, while no remarkable tensile strength deterioration rate was observed for the investigated polyvinyl chloride-coated woven polyethylene terephthalate materials. Overall, the results indicate that freeze–thaw cycles can have a significant deteriorating impact on the mechanical properties of glass-PTFE fabrics.

Fabrication, microstructure and multi-scale mechanical properties of 2.5D oxide fiber reinforced oxide composites

2.5D oxide/oxide composites have attracted substantial attention due to their good integrity. In this work, a simple process was used to manufacture the 2.5D aluminosilicate fiber reinforced alumina (2.5D-ASf/Al2O3) composites. The influence of 2.5D preform on the microstructure of the 2.5D-ASf/Al2O3 composite was studied in-depth mainly by X-ray computed tomography. Also, the change mechanism of the micro- and macro- mechanical properties of composites, especially the anisotropic mechanical properties were further analyzed. The results showed that the matrix modulus and fiber strength had great effects on the mechanical properties of the 2.5D-ASf/Al2O3 composites with different densification cycles. And the microstructure characteristics of the 2.5D-ASf/Al2O3 composites were consistent with those of the 2.5D preform, such as the warp direction cross-sections invariably had higher porosity of the pores>10 μm and larger pores than the weft direction cross-sections. This was also one of the key factors affecting the anisotropic mechanical behavior of the 2.5D-ASf/Al2O3 composites.

Effect of hybrid weaving patterns on mechanical performance of 3D woven structures

Generally, 2D woven structures are used in a different high performance applications. But 2D woven natural fibers based structures have poor mechanical properties as compared to glass and other synthetic yarns. One of the possible solutions to overcome this problem is to develop 3D woven structures with natural fibers. The present work developed hemp yarn based three types of novel 3D woven structures, i.e., hybrid through the thickness (HB-1 (TT)), novel woven layer to layer structure (HB-2 (LL)), and layer to layer structure with double warp yarn (HB-3 (LL)). Furthermore to evaluate the impact of interlocking pattern on the static mechanical properties i.e., tensile, tear, puncture resistance and stiffness tests of the strucures were performed. The findings reveal variations in tensile strength among different 3D woven structures. Specifically, the 3D woven HB-3 (LL) configuration demonstrated the highest tensile strength, whereas the HB-1 (TT) structure exhibited the lowest. In the warp orientation, the tensile strength of the 3D woven HB-3 (LL) structure surpassed that of the HB-1 (TT) structure by 25.75%. Additionally, the stiffness results for the 3D woven HB-1 (TT) structure in the warp direction exceeded those of the HB-2 (LL) structure by 55.53%. Moreover, the HB-3 (LL) structure displayed superior puncture resistance compared to other 3D woven configurations. Furthermore, in the warp direction, the tear strength of the 3D woven HB-1 (TT) structure exceeded that of the HB-2 (LL) structure by 16.40%. Statistical analysis utilizing one-way ANOVA (Tukey) revealed that the influence of 3D woven hybrid structures on the outcomes of mechanical testing was statistically significant.

Polarization Raman spectroscopy characterizations of microscopic stress in 3D angle-interlock woven composites during thermo-oxidative ageing

Investigating stress distribution of three-dimensional carbon fiber epoxy woven composites after thermo-oxidative ageing, especially the microscopic stress, is key to safety design of composite materials. Here, polarization Raman spectroscopy combined with the Raman stress sensitivity of carbon fiber was employed to characterize the microscopic stress in the carbon fiber along the warp and weft direction, as well as the microscopic stress mapping in the warp and weft interwoven interfaces. Under thermo-oxidative ageing, the carbon fiber was forced with compressive stress caused by the thermo-oxidative shrinkage of resin. The fitting lines of compressive thermo-oxidative ageing stress (TAS) distribution in the warp and weft were similar to the yarn alignment paths. Meta-regression analysis indicated that the compressive TAS in carbon fibers is positively correlated with ageing time. Furthermore, the correlation between the compressive TAS and ageing time in warp yarns is greater than that in weft yarns. The stress distributed unevenly with the synergistic effect of the structure and ageing time, and interfacial failure was generated where interfacial stresses exceeded the interfacial strength. The interfacial failure further propagated with ageing time, leading to matrix cracking.

Mechanical behavior of PVDF membrane based on the uni-/bi-axial loading experiments

Recently, composite PVDF membranes with good performance have triggered enormous interest because of their great potential application. However, the uncertainty of mechanical properties limits their application. Herein, this paper reveals the elastic modulus properties of the loading angle between warp and tensile direction using the uni-axial tensile test of SH-1050P membrane textile. In addition, the bi-axial tensile test with different loading ratios was implemented. Both uni-axial and bi-axial ductile load-displacement/stress-strain curves are featured. It is the first to establish a relationship between the elastic modulus and the loading angle using a theoretical method based on the assumption that there is no slippage and crease between yarns and matric. Furthermore, simulations with different textile parameters were carried out to verify the theoretical results. The key finding is that the elastic modulus under uni-axial load can be divided into two stages, which are elasticity and plasticity. Both of which are proportional to the sine function applied to two times the loading angle. The Poisson’s ratio of SH-1050P textile can be considered as a fixed value of 0.11. This conclusion can be extended to similar textiles. The outcome of this paper contributes to a deeper understanding of the PVDF memrane’s mechanical behavior and presents a novel insight into its response to different loading conditions.