Gotowa bibliografia na temat „Reinforcement fabrics”

AbstractThis paper introduces a knitting technique for making innovative curved three-dimensional (3D) spacer fabrics by the computer flat-knitting machine. During manufacturing, a number of reinforcement yarns made of aramid fibres are inserted into 3D spacer fabrics along the weft direction to enhance the fabric tensile properties. Curved, flat-knitted 3D spacer fabrics with different angles (in the warp direction) were also developed. Tensile tests were carried out in the weft and warp directions for the two spacer fabrics (with and without reinforcement yarns), and their stress–strain curves were compared. The results showed that the reinforcement yarns can reduce the fabric deformation and improve tensile stress and dimensional stability of 3D spacer fabrics. This research can help the further study of 3D spacer fabric when applied to composites.

Abstract Two experimental devices are used for the analysis of the deformation mechanisms of biaxial non-crimp fabric composite reinforcements during preforming. The bias extension test, commonly use for the shear behaviour characterisation of woven fabrics, allows to highlight the sliding between the two plies of the reinforcement. This sliding is localized in areas of high gradient of shearing. This questions the use of bias extension test in determining the shear stiffness of the studied reinforcement. Then a hemispherical stamping experiment, representative of a preforming process, allows to quantify this sliding. The slippage is defined as the distance, projected onto the middle surface, of two points initially opposed on both sides of the reinforcement. For both experiments, the characteristic behavior of the non-crimp fabric reinforcement is highlighted by comparison with a woven textile reinforcement. This woven fabric presents only a very little sliding between warp and weft yarns during preforming. This aspect of the deformation kinematics of the non-crimp fabric reinforcement must be considered when simulating the preforming.

Structural parameters of fabrics influence the mechanical behaviour of fabric-reinforced composites. Weft-knitted spacer fabrics have high energy absorption capacity. In this paper, low-velocity impact behavior of composites reinforced with weft-knitted spacer fabrics has been studied using energy-balance method. The effect of fabric geometry on the impact behavior of composites was investigated. A theoretical model was generated to predict the energy dissipated through the impact, considering the structural parameters of fabrics as reinforcement of composites. For this purpose, dissipated energies due to contact, membrane and bending deformation of fabrics, and buckling deformation of spacer yarns were considered. In order to evaluate the proposed model, weft-knitted spacer fabrics with two types of spacer yarn's orientation were used as reinforcement of composites. Low-velocity impact examinations were performed using the drop hammer testing machine. The results showed that the model has about 12 and 13% error in prediction of dissipated energies of different samples. Comparison between theoretical and experimental results confirms that the proposed model is capable to predict the impact behavior of weft-knitted spacer fabric-reinforced composites.

The object of the study is reinforced concrete beams that are reinforced with technical polyamide (kapron) fabric produced by Branch “Khimvolokno Plant” JSC “Grodno Azot”, and fiberglass, manufactured by JSC “Polotsk-Steklovolokno”. The relevance of the stems from the need to obtain and study experimental data of the load-bearing capacity, fracture pattern, crack resistance and cracking of reinforced concrete beams reinforced with composite fabrics, since the topic of restoring the load-bearing capacity of reinforced concrete structures or their strengthening is currently very relevant. Reinforcement of bent reinforced concrete structures with composite fabrics allows using fabrics along the outer edges of the structure, as they are resistant to the external environment and are not subject to corrosion, and represent external composite reinforcement, which, together with metal reinforcement, perceive tensile forces. The most common system for the restoration of reinforced concrete structures is currently the system of external reinforcement of carbon tapes, but the use of this material is limited by high cost. The aim of the study is to experimentally confirm the possibility of effective use of technical polyamide (kapron) fabric, produced by Branch “Khimvolokno Plant” JSC “Grodno Azot”, and glass fabric, produced by JSC “Polotsk-Steklovolokno”, to strengthen the stretched face of reinforced concrete bent structures. Two reinforcement options are presented: gluing horizontal tapes along the entire length on the lower stretched face and the device of a U-shaped clip of fabrics in the stretched zone. Experimental studies have shown that the external reinforcement of the stretched zone with technical polyamide (kapron) fabric produced by Branch “Khimvolokno Plant” JSC “Grodno Azot”, and fiberglass manufactured by JSC “Polotsk-Steklovolokno” change the nature of destruction, increase load-bearing capacity of reinforced concrete beams by 16–38 % in depending on the material and method of reinforcement, affect the crack resistance and crack formation. The results of experimental studies made it possible to solve an important applied problem of the effective use of these composite materials as external reinforcement of the tension face of bending reinforced concrete beams.

Natural lignocellulosic fibers and corresponding fabrics have been gaining notoriety in recent decades as reinforcement options for polymer matrices associated with industrially applied composites. These natural fibers and fabrics exhibit competitive properties when compared with some synthetics such as glass fiber. In particular, the use of fabrics made from natural fibers might be considered a more efficient alternative, since they provide multidirectional reinforcement and allow the introduction of a larger volume fraction of fibers in the composite. In this context, it is important to understand the mechanical performance of natural fabric composites as a basic condition to ensure efficient engineering applications. Therefore, it is also important to recognize that ramie fiber exhibiting superior strength can be woven into fabric, but is the least investigated as reinforcement in strong, tough polymers to obtain tougher polymeric composites. Accordingly, this paper presents the preparation of epoxy composite containing 30 vol.% Boehmeria nivea fabric by vacuum-assisted resin infusion molding technique and mechanical behavior characterization of the prepared composite. Obtained results are explained based on the fractography studies of tested samples.

Weft-knitted fabrics offer an excellent formability into complex shapes for composite application. In biaxial weft-knitted fabric, additional yarns are inserted in the warp (wale-wise) and weft (course-wise) directions as a reinforcement. Due to these straight yarns, the mechanical properties of such fabrics are better than those of unreinforced weft-knitted fabrics. The forming process of flat fabrics into 3D preforms is challenging and requires numerical simulation. In this paper, the mechanical behavior of biaxial weft-knitted fabrics is simulated by means of macro- and meso-scale finite element method (FEM) models. The macro-scale modelling approach is based on a shell element formulation and offers reasonable computational costs but has some limitations by the description of fabric mechanical characteristics and forming behavior. The meso-scale modelling approach based on beam elements can describe the fabric’s mechanical and forming characteristics better at a higher computational cost. The FEM models were validated by comparing the results of various simulations with the equivalent experiments. With the help of the parametric models, the forming of biaxial weft-knitted fabrics into complex shapes can be simulated. These models help to predict material and process parameters for optimized forming conditions without the necessity of costly experimental trials.

The use of textiles produced from high tenacity(HT) polyester yarns as a reinforcement material in the mechanical rubber goods industries, mainly in the conveyor belt, is extensively increasing due to their high tensile strength, flexibility, thermal stability, modulus of elasticity, and light weightiness. To achieve the desired property of a conveyor belt, the reinforcement components undergo various processing stages; among those stages vulcanizing the reinforcement materials under high temperatures is the crucial process that determines the physical and mechanical properties of the conveyor belt. The main aim of this work was to analyze the effect of vulcanization parameters on the physio-mechanical properties of high tenacity polyester yarns and fabrics that are utilized to reinforce a conveyor belt. An extensive experimental study was conducted on a pre-activated HT polyester yarn of different linear densities and woven fabrics produced for the purpose of conveyor belt reinforcement by subjecting the yarns and fabrics to various aging temperatures for a certain period of aging time. Following the experiments, a comprehensive study and analysis were conducted on the tensile property of the yarns and fabrics. The finding revealed that thermal aging has an immense impact on determining the tensile strength and elongation of the yarn and woven fabric, which also has a direct influence on the properties of the conveyor belt. The analysis of experimental test results of polyester yarns and woven fabrics revealed that vulcanizing textile-reinforced conveyor belt at high temperatures (220 °C) could deteriorate the tensile strength and increase the elongation at break of the yarn, fabric, or belt.

Thermal conductivity data for dry carbon fibre fabrics are required for modelling heat transfer during composites manufacturing processes; however, very few published data are available. This article reports in-plane and through-thickness thermal conductivities measured as a function of fibre volume fraction ( Vf) for non-crimp and twill carbon reinforcement fabrics, three-dimensional weaves and reinforcement stacks assembled with one-sided carbon stitch. Composites made from these reinforcements and glass fibre fabrics are also measured. Clear trends are observed and the effects of Vf, de-bulking and vacuum are quantified along with orthotropy ratios. Limited differences between the conductivity of dry glass and carbon fibre fabrics in the through-thickness direction are reported. An unexpected trend in the relationship between that quantity and Vf is explained summarily through simple simulations.

This paper examines critical issues associated with the fabrication and forming of highly-flexible polymeric composites, reinforced with knitted-fabric structures. Knitted-fabric reinforcements have not generally been preferred over more traditional woven reinforcements in high-performance composites, mainly because of their lower stiffness/strength performance when embedded in a rigid, thermosetting matrix material. However, with their unique formability, knitted fabrics promise great potential in applications where large deformation of the structure is desirable; such as energy/impact absorption and forming applications. One very attractive feature of knitted composite materials, is the large displacements that the underlying knitted fabric can potentially undergo before exhibiting a significant increase in stiffness. The unusual extensional behavior of knit fabric is attributed to the fact that the fibers are more-or-less free to slide over each other before the yarns become highly oriented, eventually “locking” in a packed formation. When the loops become highly elongated, the knit fabric achieves its maximum resistance to in-plane deformation, and exhibits a stiffness closely related to the elastic stiffness of the straightened fiber/yarn bundles. The unique formability of knitted fabrics is mainly due to this yarn movement. The highly “stretchable” behavior of knitted textile reinforcement materials can be used to great advantage in thermoforming composite structures. In order to fully utilize the exceptional stretch properties of the knitted-fabric, the matrix material should be able to deform at least as much as the fabric, and the knitted yarn movements need to be restricted by the matrix as little as possible. In this study, a multi-level finite element procedure was developed to analyze and control the deformation characteristics of plain weft knit reinforced composites. A database of mechanical properties for various knit geometries was obtained. Using these results, it is shown that carefully “tailored” knit fabric reinforcement can be used to improve mechanical performance and facilitate polymer forming processes, such as thermoforming. In this study, elastomeric materials such as polyurea and thermoplastic elastomer (TPE) were used to fabricate composites with knitted-fabric. Two different types of arrangements were experimentally studied: knitted fabric embedded in the elastomer and a sandwich of knitted fabric between elastomeric skins. It is shown that by fully utilizing the high stretchability of the knitted fabric reinforcements, attractive material properties can be obtained especially for energy/impact absorption and forming applications. The improvement of thermoforming process stability with the use of carefully tailored knitted fabric reinforcements is also presented.

AbstractFabric-based laminated composites are used considerably for multifaceted applications in the automotive, transportation, defense, and structural construction sectors. The fabrics used for composite materials production possess some outstanding features including being lighter weight, higher strength, and lower cost, which helps explain the rising interest in these fabrics among researchers. However, the fabrics used for laminations are of different types such as knit, woven, and nonwoven. Compared to knitted and nonwoven fabrics, woven fabrics are widely used reinforcement materials. Composites made from fabric depend on different properties such as fiber types, origin, compositions, and polymeric matrixes. Finite element analysis is also further facilitating the efficient prediction of final composite properties. As the fabric materials are widely available throughout the world, the production of laminated composites from different fabric is also feasible and cost-effective. This review discusses the fabrication, thermo-mechanical, and morphological performances of different woven, knit, and nonwoven fabric-based composites.