Multiaxis three-dimensional circular woven preforms - "radial crossing weaving" and "radial in-out weaving": preliminary investigation of feasibility of weaving and methods

The aim of the study is to develop new preform structures and processes to use in the technical textile and composite industries. Multiaxis and orthogonal three-dimensional (3D) circular woven preforms and weaving methods have been developed. The multiaxis structure has five yarn sets as (+/-)bias, axial, circumferential, and radial yarns whereas the orthogonal structure has three yarn sets, axial, circumferential, and radial yarns. Two weaving methods, radial crossing and radial in-out weaving were introduced to form the structures. An experimental rig was constructed to evaluate the methods. Basic process and structure parameters have been identified. The preliminary studies showed that the multiaxis 3D circular woven preforms and methods seemed feasible

Plain para-aramid/phenolic multiwall carbon nanotubes prepreg/multistiched preform composites: Experimental characterization of mode-I toughness

The fracture toughness (mode-I) properties of nanostitched para-aramid/phenolic multiwall carbon nanotube prepreg composites were investigated. The fracture toughness (G(IC)) of the stitching and nanostitched composites showed 42-fold and 41-fold (beam theory), 18-fold and 21-fold (modified beam theory) increase compared to the control, respectively. The prepreg para-aramid stitching yarn and nanostitched yarn were dominant parameters. The toughness resistance to arrest crack growth in the nanostitched composite was primarily due to nanostitching fiber bridging and pull-out, and was secondarily due to nanotubes and biaxial fiber bridging and pull-out. The failed surfaces of the nanostitched and stitching composites had tensile filament failures in the aramid stitching fibers where filament/matrix/nanotube debonding and axial filament fibrillar splitting were found. The results indicated that stitching yarn and the nanotubes arrested the crack propagation. Therefore, the nanostitched and stitched para-aramid/phenolic composites displayed a better damage resistance performance compared to those of the control or nanotube composites

Compression after low-velocity impact (CAI) properties of multistitched composites

The objective of this work was to investigate compression after low-velocity impact (CAI) properties of a multistitched composite. It was found that the CAI strength of the multistitched composite was high compared to the unstitched composites. In addition, stitching density, stitching type, stitching direction, and stitching fibers were found to be important structural parameters. The CAI load on the multistitched composites resulted in lateral damages near the impacted indentation region. The structures showed large damaged areas, but the out-of-plane layer delamination was confined to relatively small areas. Thus, the multistitching enhanced the CAI properties of the composite

Multilayered and Multidirectionally-stitched aramid Woven Fabric Structures: Experimental Characterization of Ballistic Performance by Considering the Yarn Pull-out Test

The aim of this study was to understand the energy absorption mechanism and failure modes of newly developed multidirectionally-stitched structures. Para-aramid woven fabric was used. The structures were in unstitched and stitched forms. Nylon 6.6 yarn was used to stitch the structure in one, two and four directions whereas Kevlar (R) 129 yarn was used to make only the four-directionally-stitched structures. The yarn pull-out fixture was developed and the yarn pull-out test was performed on single woven fabric and stitched structures. Ballistic tests were performed on the structures using 9 mm full metal jacketed projectiles with a speed of 300 to 400 m/s. If the applied kinetic energy level is under the yarn breaking extension, crimp in the orthogonal yarns at the fabric structure is firstly removed, and thereafter yarn pull-out takes place in the structure plane, and later stage fabric deformation occurs in the out-of-plane direction of the structure. This phenomenon continues from the outside to the inside layers. If the applied kinetic energy level is above the yarn breaking extension, firstly partial and total filament breakages and subsequently crimp removal and yarn pull out stages occur. These phenomena take place as multiple yarn failure in the outer layers and mostly crimp removal and yarn pull-out towards the inside layers occur. In both cases, fabric and structure bending were ignored. The energy absorption level of the stitched structures was slightly higher than that of the unstitched structures due to the fact that some of the energy was absorbed to delaminate the interlayer, which was locked by the stitching yarns. Also, the conical depth in the stitched structure was low compared with that of the unstitched structure

Tearing properties of upholstery flocked fabrics

We have studied the tearing strength of substrate woven fabric, substrate with adhesive, flocked fabric and washed flocked fabric on dry and wet conditions. The tensile strength of the rubbed flocked fabric and rubbed washed flocked fabrics in dry and wet conditions were also researched, and a statistical model was developed for the analysis of the tearing behavior of these fabric forms.Warp and weft tearing strengths of rubbed flocked fabric and rubbed washed flocked fabric in wet conditions were slightly higher than those in dry conditions. The reason was partly the high wet strength characteristic of cotton fiber and partly the lubrication effect of acrylic adhesive under wet conditions. Although the weft density of the substrate fabric was around half of its warp density, there was a small difference between warp and weft tearing strengths of dry and wet states of rubbed flocked fabric. This was attributed to the dense structure having less free space and less ultimate deformation potential and ultimately reducing the tearing strength.When the stroke number increased, the warp and weft tearing strengths of dry and wet states of rubbed flocked fabric generally decreased. It was also found that the stroke number of wet rubbed flocked fabric and rubbed washed flocked fabric was low in comparison with stroke number of dry rubbed flocked fabric and rubbed washed flocked fabric. The reason was that the wet acrylic adhesive had poor properties.The results from the regression model were compared with the measured values mainly by the mean absolute percent error parameter which enables us to conclude that the developed regression equations explain the tearing strength of flocked fabrics

Analysis and tensile characterization of flocked fabric after rubbing

In this study, the tensile properties of flocked fabric after rubbing were studied. A statistical method was used to analyze the generated data. For this purpose, woven fabric was used as a substrate and an acrylic adhesive was applied on this substrate to hold the polyamide flock fibers forming flocked fabrics. A rubbing test was applied in dry and wet forms to the flocked fabrics before and after washing. The tensile properties of these rubbed flocked fabrics were determined. The regression models developed in this study explain the relationship between rubbing and the tensile strength of the flocked fabrics. The results from this experiment could be used in the development of flocked fabric as seat covers for the automotive industry. The warp tensile strength of a flocked fabric is generally higher than its weft tensile strength due to its higher substrate density in the warp direction. Also, the weft tensile elongation of a flocked fabric is generally higher than its warp tensile elongation due to its higher crimp ratio in the weft direction. When the stroke number increases, the warp and weft directional tensile strength and the elongation of a flocked fabric generally decrease. In addition, the stroke number of a flocked fabric before and after washing is low in its wet form compared to the dry form. The main reason is that the acrylic adhesive has poor wet properties. Results from the regression models were compared with the measured values. It was concluded that the method used in this study could be a viable and reliable tool. © 2011 The Textile Institute

Bioprocessing of natural textile fibres and clothes

Textile finishing is a crucial step in making fibre-based materials more appropriate by providing the final properties to the textile product. Various chemicals and processes are employed by combining scientific principles, following analysis and modelling based on data generation, by the use the innovative methods. Therefore many studies and researches are carried out on textile finishing processes and chemicals. In this context, the use of enzymes has become more common and current developments in this regard are scientifically examined and researched. Because of their ability in performing harsh processing conditions-reactions in temperate conditions biospecifically-enzymes attract the interest of textile finishers. In addition, their ability to modify the basic fibre properties and make them more useful for textile applications constitute the other feature of enzymes. In this chapter, the usability of enzymes in the finishing of natural fibres is presented and current mostly experimental studies are discussed. © 2021 Elsevier Ltd All rights reserved