Stab resistance of flexible composite reinforced with warp-knitted fabric like scale structure at quasi-static loading

The stab-resistant fabric like scale structure has a promising application prospect for areas of stab prevention owing to its great flexibility and excellent stab-resistance performance. In this paper, a kind of novel stab-resistant fabric has been designed by coating with epoxy resin (ER) and silicon carbide (SiC) particles, which was based on the warp-knitted fabric like scale structure (WKFS). The uniformity of dispersion has been investigated with different diameter and mass fraction of SiC, and polymerization degree of polyglycols (PEG); the flexibility and quasi-static properties of different kinds of WKFS treated with different coating solution has been studied, and the coating solution was prepared by mixing SiC particles and ER at different ratios. The results showed that the dispersion uniformity of the dispersion was the best when the diameter of SiC is 1 μm, the content is 50%, and the polymerization degree of PEG is 600. The longitudinal flexibility of the stab-resistant fabric is greater than that of transverse due to the gap between the longitudinal scales, and the addition of SiC particles can increase the transverse and longitudinal flexibility of stab-resistant fabric, and the flexible properties were the greatest when SiC:ER = 50:30. In addition, the WKFS treated with SiC of 16.7% has fatigue resistance; the damage mechanism of the fabric treated with pure ER is thankful to the brittleness of the resin; the added SiC particles hinder the further crack propagation of the resin, and the failure mode is mainly in stretch.

A Calculation Method for the Deformation Behavior of Warp-Knitted Fabric

In this paper, a new method to simulate the structure and loop deformation behavior of double-bar reflex-lapping warp-knitted fabrics based on the structural characteristics is proposed. A simplified mass-spring model was built in which loops knitted by filaments were considered as particles with the uniform mass distribution connected by structure springs for overlaps and shear springs for underlaps. Deformation forces and direction on particles were analyzed to describe the displacement and deformation behavior of particles. A loop model with eight control points was established, and the relationship between control points and particles was studied combining the quadratic Bezier curves. The deformation simulation was implemented by a simulator program with C# and JavaScript via web technology on Visual Studio 2015. The stereoscopic sense of filaments was realized by changing the direction and intensity of the light. The results show that the fabric deformation and the loop shape can be accurately achieve using the simplified mass-spring model compared with the real sample.

An intelligent defect detection system for warp-knitted fabric

In textile factories, the most typical warp-knitted fabric defects include point defects, holes, and color differences. Traditional manual inspection methods are inefficient for detecting these defects. Existing intelligent inspection systems often have a single function. Factories require a real-time inspection system that can detect common defects and color difference. The YOLO (you only look once) neural network is faster than the two-stage neural network and has lower hardware requirements. The system’s color difference detection algorithm compares the color difference between the standard image and the image to be measured and records where the color difference value is exceeded. Finally, the comparison of the factory application proves that the designed system has good real-time performance and accuracy and can meet the fabric inspection requirements of warp-knitted fabric factories.

Long-term viability and extensibility of an in situ regenerated canine aortic wall using hybrid warp-knitted fabric

OBJECTIVES Many surgical materials promoting tissue regeneration have been explored for use in paediatric cardiac surgery. The aim of this study is to evaluate the long-term viability and extensibility of the canine aortic wall regenerated using a novel synthetic hybrid fabric. METHODS The sheet is a warp-knitted fabric of biodegradable (poly-l-lactic acid) and non-biodegradable (polyethylene terephthalate) yarns coated with cross-linked gelatine. This material was implanted as a patch to fill an oval-shaped defect created in the canine descending aorta. The tissue samples were explanted after 12, 24 or 36 months (N = 3, 2, 2, respectively) for histological examination and biomechanical testing. RESULTS There was no shrinkage, rupture or aneurysmal change after 24 months. The regenerated wall showed prototypical vascular healing without material degeneration, chronic inflammation, calcification or abnormal intimal overgrowth. Bridging tissue across the patch was well-formed and had expanded over time. The biodegradable yarns had completely degraded at 24 months after implantation, as scheduled, but the regenerated aortic wall demonstrated satisfactory levels of mechanical strength and extensibility in tensile strength tests. CONCLUSIONS The sheet achieved good long-term viability and extensibility in the regenerated aortic wall. These findings suggest that it is a promising surgical material for repairing congenital heart defects. Further developments of the sheet are required, including clinical studies.

Auxetic behavior of warp knitted fabric under repeating tension

In our previous study, a novel class of auxetic warp knitted fabrics were developed and their auxetic behaviors were studied under a single tensile test. However, during daily use, the fabrics are usually subjected to repeating tension rather than single tension. Therefore, the durability of the fabrics’ auxetic performance is of great importance. So far, the auxetic behavior of fabrics under repeating tension has not systematically been investigated. In this paper, we report a study on the auxetic behavior of warp knitted fabrics under repeating tension. All the fabric samples were subjected to a repeating tensile test within a tensile strain of 25% until 100 tensile cycles. The results show that the fabrics can keep their auxetic effect in both course and wale testing directions after 100 tensile cycles, and the auxetic effect in the wale direction is retained longer under higher tensile strains than that under lower tensile strains with the increase of tensile cycles. The results also indicate that auxetic stability in the course direction is much better than that in the wale direction. We hope that this study can offer useful information to improve the auxetic stability of auxetic fabrics for practical use.

Preparation and moisture management performance of double guide bar warp-knitted fabric based on special covering structure

This article provides a knitting method for warp-knitted fabrics with good moisture management performance. By adjusting of the warp knitting machine (mainly the bar), the design of lay-up method of the yarn, the selection of the yarn, and the warp let-off tension, the yarn covering relationship has been adjusted. By using two kinds of fineness polyester DTY, cotton yarn and spandex, designing two kinds of warp-knitting structures, six different warp-knitted fabrics have been knitted. The moisture management performance of these knitted samples was compared and evaluated. The study found that the greater the difference between the inner yarn and the outer yarn, the better the moisture management ability of the fabric. Polyester DTY with 50D/14F on the inner side and polyester DTY with 75D/288F on the outer side have the best moisture management performance. The polyester DTY with 50D/14F on the inside and 9.83Tex cotton yarn on the outside have higher wetting time and absorption rate.

The friction and wear behaviors of self-lubricating composites with two types of warp-knitted fabric structures

Replacing the traditional self-lubricating fabric composites with new type of wear-resistant composite reinforced by warp-knitted fabrics PTFE-Nomex and PTFE-Nomex/Nomex (self-lubricating fiber: PTFE, reinforcing fiber: Nomex), in which the hybrid graphite/graphene particle modified phenolic is used as the adhesive resin. The influence of the fabric structure on the friction and wear properties of self-lubricating fabric composites was evaluated by the ball-on-disk and bearing friction tests. And the wear mechanism of the composites was investigated through scanning electron microscopy (SEM) and mechanical tests. The ball-on-disk friction test shows that the friction and wear properties of two kinds of composites with different structures are different with the increase of friction distance. In addition, the self-lubricating warp-knitted composite materials were prepared as self-lubricating joint bearing liners to evaluate the bearing application. It is proposed that the wear resistance of the two kinds of warp-knitted composites is poor, and the single layer is slightly better. It is related to the friction mode, mechanical and bonding properties of the bearing liners.

A shortened development process method for warp-knitted yarn-dyed shirt fabric

At present, warp-knitted yarn-dyed shirt fabric has become the research focus due to its comfort and highly efficient production. In order to shorten the development process of warp-knitted yarn-dyed shirt fabric, a computing method including theoretical modeling and simulation is proposed in this paper to simulate 2–5 guide bar warp-knitted yarn-dyed shirt fabric. Based on the structure model of warp-knitted fabric, a new model of geometric shape, including loops and underlap, is built according to size measurement results of the loops. In terms of the establishment of mathematical models, such as models of yarn-pressing, loop types, loop locations, guide bar threading, color and fineness, the transformation between knitting technology and mathematical language is realized. With the double buffer technique of HTML (Hypertext Markup Language), loops and underlaps of each bar are displayed separately on different canvases superposed in some order. Simulation is implemented for 2–5 bar warp-knitted yarn-dyed shirt fabric via JavaScript and C# programming languages. The results indicate that this method is able to simulate diverse 2–5 bar warp-knitted yarn-dyed shirt fabrics in a short time. The pattern effect can be seen with a high similarity and practicability before it is produced, thereby shortening the development.