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The yarn level modelling of warp knitted structures is a complex process. For structures placed on the plane, it is well investigated and there are a few software solutions and papers reported. This paper considers the simulation of warp knitted structure, deformed in the 3D space. Especially the modelling of the areas of high curvature are detailed observed. Underlaps with longer lengths makes an unreal visualization for simulation results. Different pattern with different length of the underlaps are modelled with original algorithm developed by the authors. Modelling and visualization problems in the areas with long underlaps are discussed and possible solutions are proposed.

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.

PurposeThe purpose of this research is to propose a flexible sensor with a weft-knitted float stitch structure and to explore knitting techniques that allow conductive yarns to be skin-tight and less exposed, reducing production processes and increasing productivity. Study its electrical conductivity in different yarn materials, knit processes and deformation ranges. The analysis is compared to provide some basis for the design of the electrodes.Design/methodology/approachThe method includes five operations: (1) Analysis of the morphological appearance, tensile variation, fiber material properties and electrical conductivity of high-elastic and filament silver-plated conductive yarns. (2) Based on the knitting process of the floating yarn structure, three-dimensional modeling of the flexible sensor was carried out to explore the influence of knitting process changes on appearance characteristics. (3) The fabric samples are knitted by different silver-plated conductive yarns with different structures. Processing of experimental samples to finished size by advance shrinkage. (4) Measure the resistance of the experimental sample after the machine has been lowered and after pre-shrinking. Use the stretching machine to simulate a wearing experiment and measure the change in resistance of the sample in the 0–15% stretching range. (5) Analyze the influence factors on the conductive performance of the flexible sensor to determine whether it is suitable for textile flexible sensors.FindingsFor the float knitted flexible sensors, the floating wire projection is influenced by the elasticity of the fabric and the length of the floating wire. Compared to the plain knitted flexible sensors, it has less resistance variation and better electrical properties, making it suitable for making electrodes for textile structures. In addition, the knitting method is integrated with the intelligent monitoring clothing, which saves the process for the integration of the flexible sensor, realizes positioning and fixed-point knitting.Practical implicationsThe sensor technology of the designed weft-knitted float structure is varied and can be freely combined and designed in a wide range. Within the good electrical conductivity, the flexible sensor can realize integrated knitting, positioning monitoring, integrating into the appearance of clothing. It can also focus on the wearing experience of wearable products so that the appearance of the monitoring clothing is close to the clothes we wear in our daily life.Originality/valueIn this paper, an integrated positioning knitting flexible sensor based on the weft knitting float structure is studied. The improved knitting process allows the sensing contact surface to be close to the skin and reduces the integration process. The relationship between the exposure of the silver-plated yarn on the clothing surface and the electrical conductivity is analyzed. Within a certain conductive performance, reduces the exposed area of the conductive yarn on the clothing surface and proposes a design reference for the flexible sensor appearance.

The purpose of this paper is to geometrically simulate warp-knitted medical tubular bandages with a computer-aided simulator. A flat mesh model is established according to unfolded fabric considering the knitting characteristics of double-needle bed warp-knitted tubular fabrics. Moreover, a 3D (three-dimensional) mesh model corresponding to the actual product shape is created. To better describe the spatial geometry of stitches, eight-point models are introduced, and stitches are generated with the flat mesh model. Founded on matrix operations, the stitch position in the 3D mesh model is determined through coordinate mapping. Various stitch paths are rendered in computer programming languages C# and JavaScript to conduct simulations. Warp-knitted medical tubular bandages with a large number of shapes are effectively modeled.

To realize high-speed running of a warp knitting machine, the shogging motion should not only meet the requirement of high dynamic response but should also satisfy high positioning accuracy. Due to the large location disturbance and the dynamic response delay in the interpolation method or the single velocity planning curve method, an electronic shogging system for a warp knitting machine based on the mixed-velocity planning curve is proposed in the present study. Through the analysis of the shogging motion combined with the knitted structure, the optimal resolution of the instruction signal is calculated, which is 725 pulses for one needle step, and the velocity loop bandwidth of the servo driver is optimized. In addition, the motor with a load inertia ratio close to 1 is also selected. Analysis of the shogging motion vibration curve confirms that the shogging motion has advantages of high positioning accuracy and high dynamic response under the mixed-velocity planning curve. The response performance with the mixed curve is 12.5% higher than that with the quintic polynomial, and the positioning accuracy of the mixed curve is 26% higher than that with uniform acceleration–deceleration curve.

This article concentrates on a geometric-based simulation method for warp-knitted tubular fabrics. The warp-knitted tubular fabric is unfolded as a two-dimensional flat fabric after analyzing the s...

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.

PurposeThe size prediction of garment is an important part in the process of the garment design and production, and it is also one of the most important features in warp-knitted computer-aided design system. The purpose of this paper is to realize the auto-generation of the garment templates using JavaScript and WebGL technologies, based on the prediction of the size of warp-knitted seamless sportswear.Design/methodology/approachThe warp-knitted jacquard technology is used to produce the warp-knitted seamless sportswear, which is divided into suits and tights. In order to achieve the purpose of this study, the dimensions of four kinds of jacquard patterns knitted under different knitting conditions are measured and the crosswise and longitudinal size shrinkage percentages are also calculated. Then, the relationship between the yarn count and the drawing density as well as the size shrinkage percentage is studied and a size prediction model for warp-knitted jacquard fabric is established. Next, according to the results of the size calculation, the point positions of the garment boundary in the mathematical coordinate system is determined. The color formula is built by the two-dimensional mathematical matrix. Finally, combined with the coordinate position and color information, the template can be drawn automatically.FindingsBased on the size prediction model of warp-knitted garment, the template generation of warp-knitted full-form sportswear on WebGL-enabled web browser is realized, which is proven to be an effective computer-aided design method for warp-knitted garments.Research limitations/implicationsBecause of limited researches, only two groups of yarns and four kinds of jacquard patterns were studied. A vaster database should be built and smooth curve, accurate coordinate needs to be optimized in the further research.Practical implicationsThe size prediction model for warp-knitted jacquard garment and garment template auto-generation of warp-knitted computer-aided design system will simplify the fabric technical design process, shorten design time and improve the efficiency of new product development.Social implicationsThe size prediction model for warp-knitted jacquard garment and garment template auto-generation of warp-knitted computer-aided design system will provide the industries a guidance for new sample development and it also can shorten the development time and lower cost.Originality/valueThis author analyzes the relationship between the size characteristics and knitting technology of warp-knitted jacquard patterns, proposes a model of size prediction and realizes the auto-drawing of the garment template in the warp-knitted CAD system, which provides a reference for the new product design and development of warp-knitted seamless sportswear.

Modeling fabrics with yarn models makes the fabric structure more realistic in detail. In this paper, a fiber-level rendering method is proposed to simulate different yarns and fabrics. The fibers are divided into three categories: the ply, the loop hairiness and the short hairiness. Geometric tubes are modeled to match these fibers according to the input yarn parameters. Different fibers can be selected depending on the yarn type, which is flexible to reduce the computation amount. Texture mapping is applied to simulate the yarn surface, reducing the memory and time cost of rendering large numbers of fibers. Several single yarns and fabric with different structures are simulated, demonstrating that this is an effective method for fabric modeling and rendering.

Warp-knitted spacer fabrics (WKSFs) with multi-layers, one of the extraordinary promising materials, are of great significance for structural uses in aerospace, military, construction, building, transportation, and so on. Compressive property is one of the important properties of WKSFs with multi-layer. In order to better understand the flat plate compressive mechanism of WKSFs with multi-layers, simplified models of WKSFs with multi-layers were constructed and their flat plate compression behaviors were simulated by finite element method. The relationship between the number of layers and compressive performance of WKSFs with multi-layers was studied by combining experiment and finite element simulation. The results showed the spacer monofilaments bear the main stress during the compression process. And the larger stress appears at the inflection point of the spacer monofilaments where the bending is serious and contact points among WKSFs with multi-layers. The compressive stiffness increases with the increase of layers in the later stage of compression. The developed finite element models have successfully simulated the flat plate compression stress-strain relationships of WKSFs with multi-layers, which are basically consistent with the general trend of test results, revealing the compression deformation mechanism and providing theoretical reference for the practical application of WKSFs with multi-layers.

An online garment model reconstruction method is proposed using the axial deformation to simulate the various garment models to display the wearing effect under different sizes. The garment model is classified into three categories according to the structural features. The main sections and key points are determined based on the existing dimensional features. Inverse operation and radial weight are used in the garment deformation. Texture mapping is applied to the model reconstruction result to obtain a new model with clothing patterns. An online system is developed and garment models with multiple scales are applied to adapt to various devices. The reconstruction results are compared and analyzed, which proves that the method proposed can realize real-time 3D reconstruction of garment models with the changing sizes on the web page.

In this paper a mathematical model of looped warp knitted jacquard fabric is proposed. The technology parameters cover chain notation, threading, jacquard pattern grid and so on are defined based on the matrix. A basic pattern matrix is derived from chain notation and threading using the block matrix. Then combined with the displacement data of jacquard girds, the jacquard pattern matrix is calculated. Finally, the stitch type and stitch position are obtained analyzing the pattern information in the previous matrix. Special stress is laid on the difference between two different displacement data of jacquard girds, RT = 0 and RT = 1, which results in inconsistent lapping for the same jacquard bitmap. The pattern models are implemented and the jacquard lapping bitmap and three-dimensional simulation are generated by a calculating program via Visualstudio2015 using C# and JavaScript. The results show that this model can distinguish two types displacement jacquard information. The parameter input process is simplified and the run time for calculation is also shortened. In addition, with the help of CAD system via the web, priorities including resource sharing, design-time saving, and efficiency improving are achieved.