Effect of Silicone Inlaid Materials on Reinforcing Compressive Strength of Weft-Knitted Spacer Fabric for Cushioning Applications

Spacer fabrics are commonly used as cushioning materials. They can be reinforced by using a knitting method to inlay materials into the connective layer which reinforces the structure of the fabric. The compression properties of three samples that were fabricated by inlaying three different types of silicone-based elastic tubes and one sample without inlaid material have been investigated. The mechanical properties of the elastic tubes were evaluated and their relationship to the compression properties of the inlaid spacer fabrics was analysed. The compression behaviour of the spacer fabrics at an initial compressive strain of 10% is not affected by the presence of the inlaid tubes. The Young’s modulus of the inlaid tubes shows a correlation with fabric compression. Amongst the inlaid fabric samples, the spacer fabric inlaid with highly elastic silicone foam tubes can absorb more compression energy, while that inlaid with silicone tubes of higher tensile strength has higher compressive stiffness.

Design, Development, and Characterization of Advanced Textile Structural Hollow Composites

The research is focused on the design and development of woven textile-based structural hollow composites. E-Glass and high tenacity polyester multifilament yarns were used to produce various woven constructions. Yarn produced from cotton shoddy (fibers extracted from waste textiles) was used to develop hybrid preforms. In this study, unidirectional (UD), two-dimensional (2D), and three-dimensional (3D) fabric preforms were designed and developed. Further, 3D woven spacer fabric preforms with single-layer woven cross-links having four different geometrical shapes were produced. The performance of the woven cross-linked spacer structure was compared with the sandwich structure connected with the core pile yarns (SPY). Furthermore, three different types of cotton shoddy yarn-based fabric structures were developed. The first is unidirectional (UD), the second is 2D all-waste cotton fabric, and the third is a 2D hybrid fabric with waste cotton yarn in the warp and glass multifilament yarn in the weft. The UD, 2D, and 3D woven fabric-reinforced composites were produced using the vacuum-assisted resin infusion technique. The spacer woven structures were converted to composites by inserting wooden blocks with an appropriate size and wrapped with a Teflon sheet into the hollow space before resin application. A vacuum-assisted resin infusion technique was used to produce spacer woven composites. While changing the reinforcement from chopped fibers to 3D fabric, its modulus and ductility increase substantially. It was established that the number of crossover points in the weave structures offered excellent association with the impact energy absorption and formability behavior, which are important for many applications including automobiles, wind energy, marine and aerospace. Mechanical characterization of honeycomb composites with different cell sizes, opening angles and wall lengths revealed that the specific compression energy is higher for regular honeycomb structures with smaller cell sizes and a higher number of layers, keeping constant thickness.

Mechanical properties of the surface membrane of lattice spacer-fabric flexible inflatable composites

The surface membrane plays a vital role in bearing loads of flexible inflatable composites. In this work, the mechanical properties of the upper and lower surfaces of inflatable composites and spacer fabrics were studied. It focused on the changes in mechanical properties of surfaces of spacer fabrics with different structures after coating and damage characteristics. The results show that the PVC resin improves the mechanical properties of the surface, which penetrates into the structure to make the yarns bond to each other and adhere to the resin on the surface. And compared with knitted structures, composite membranes with a woven structure have the characteristics of specific strength. This provides data accumulation for performance research of flexible inflatable composites, finite element calculation analysis, and the experimental reference for broadening the application in military pontoons and marching tents.

Double-appearance patterning model of warp-knitted spacer textiles based on the jacquard loop index

This research focuses on a three-dimensional jacquard spacer fabric, which has two sets of jacquard yarn systems to form double-appearance patterns. Because of the unique structure and formation characteristics, a specific computerized patterning model needs to be solved for efficient jacquard structure design. After a systematic analysis of double-needle bed knitting and the piezo-jacquard principle, a loop index is proposed to coordinate jacquard loops and define the single-loop-based jacquard bitmap. Also, an algorithm is derived to solve offset data to guide the knitting action by inferring the jacquard bitmap and the corresponding loops hypotaxis. This new patterning method is proposed based on two basic elements of the jacquard bitmap and lapping data. In comparison with the traditional two-course bitmap method, the new approach shows the advantage of more simplified operations by a significant decrease of jacquard color definitions.

Yhe Compression Meso-Mechanics Theoretical Model and Experimental Verification of Polyurethane-Based Warp-Knit Spacer Fabric Composites

In this research, a new type of binary material, a polyurethane-based warp-knitted spacer fabric composite (PWSF), having a unique three-dimensional structure, high strength, and a variety of surface structures was prepared. The compression meso-mechanics theoretical model based on the Winkler elastic foundation beam theory and structural parameters of PWSF were used to predict the compression performance of PWSF. To verify the validity of compression model, the compression stress-strain curves of theoretical simulation were compared with the quasi-static compression test results. The deviation between these two compression moduli was less than 7%. The compression meso-mechanics model established in this study can effectively simulate the actual compression behaviors for different PWSF specimens. A regular pattern of compression properties of this novel composite from the theoretical research on meso-mechanics perspectives can be proposed.

Design and manufacture of three-dimensional auxetic warp-knitted spacer fabrics based on re-entrant and rotating geometries

Warp knitting technology is a fabric-forming technologies that is very suitable to fabricate three-dimensional (3D) auxetic fabrics due to its high efficiency and powerful pattern designing possibilities. In this study, two typical auxetic geometries, namely the re-entrant hexagonal network and rotating square solids, were selected as the design prototypes for the design and manufacture of 3D warp-knitted spacer fabrics. While two 3D warp-knitted spacer fabric structures with representative units of different sizes designed based on the re-entrant hexagonal geometry were manufactured by using a RD7 double needle bar Raschel machine with seven yarn guide bars, two 3D jacquard warp-knitted spacer fabrics with different base fabric structures designed based on the rotating squares geometry were fabricated by using a RDPJ4/2 double needle bar jacquard machine with two ground yarn guide bars and four jacquard guide bars. The Poisson’s ratios of these 3D warp-knitted fabrics in the course direction and wale direction were evaluated respectively through constant-rate tensile tests. The results revealed that the re-entrant hexagonal fabric structure with double chain stitches has auxetic behavior across a wide range of tensile strains along the course direction, while the rotating square fabric structure with elastic chain stitches as the base is auxetic within a narrow range of tensile strains along the wale direction. The study provides an alternative method to directly produce auxetic warp-knitted spacer fabrics through a single knitting process instead of using an additional post-compression and heat-setting process.

The study of hydrophobicity and oleophilicity of 3D weft-knitted spacer fabrics integrated with silica aerogels

The interest in multifunctional textile materials has been increased due to the health and safety measures of living beings, especially in severe conditions. Therefore, this study investigated the hydrophobicity, oil sorption capacity, and bending properties of untreated or uncoated and treated or coated 3D weft-knitted spacer fabric samples (92% polyester/8% spandex), i.e. sample 1, sample 2, and sample 3, having thicknesses of 2 mm (300 gm−2), 3 mm (350 gm−2), and 4 mm (540 gm−2), with silica aerogels (SAs) through the sol-gel method. SEM, FTIR-ATR, and surface roughness test of fabric samples were analyzed to comprehend the influence of SAs. The experimental results revealed the excellent hydrophobicity and oleophilicity of all the treated 3D weft-knitted spacer fabric samples, providing a higher water contact angle (CA) 142 ± 0.84° and an oil sorption capacity 7.51 ± 0.08g/g and 6.88 ± 0.06g/g for vegetable oil and engine oil, especially of sample 2 owing to the most silica particles. The statistical analysis also demonstrated a significant performance (P < 0.05) of treated spacer fabric samples at the 0.05 level. Thus, these fabrics are suitable for an industrial application of hydrophobic and oleophilic properties.

Lattice modeling for the influence of geometrical patterns of 3D spacer fabric on tensile behavior of concrete canvas

Tensile behavior of concrete canvas (CC) mainly depends on the geometric patterns of 3D spacer fabric. A lattice model is proposed to model the three-dimensional structure of CC to investigate the influence of geometric patterns of 3D spacer fabric on the tensile behavior of CC. The stress intensity factor is also applied into the lattice model to study the crack development of CC subjected to tensile load. The simulation results are compared to the experiments to verify the model. Finally, the influence of geometric pattern of outer layer and spacer yarns on tensile behavior of CC are simulated based on our proposed lattice model. The results indicate that the tensile strength of CC increases as the loop unit size of outer surface decreases or the amount of spacer yarns increases; the tensile strength of CC with rhombus loop unit of outer surface layer is higher than that of CC with rectangle loop unit. The tensile strength of CC significantly increases with the increasing inclination angle of spacer yarns in 3D spacer fabric. Furthermore, CC specimens subjected to uni-axial tensile exhibit a multi-cracking behavior, the average crack spacing of specimen decreases with the decreasing inclination angle of spacer yarns in tensile direction.