Electro-Mechanical Properties of Knitted Fabric Made From Conductive Multi-Filament Yarn Under Unidirectional Extension

Abstract

A theoretical model for electro-mechanical properties of intrinsically conductive knitted fabrics made from stainless steel multi-filament yarns under large uniaxial deformation is presented. The investigations are focused on the relationship between the load and electrical resistance of the fabric under uniaxial extension. A circuit network is proposed based on the loops configuration and fabric structure. The equivalent resistance of the fabric is obtained by solving the circuit equations of the network. In order to simplify the calculation of the contacting forces on the overlapped yarns, a two-dimensional hexagon model is used to represent the loop configurations. An image-capturing system is employed to record the images of the loop configurations during the extension process and the relationship between the configurations of the loops and the load imposed on the fabric is obtained. From the theoretical analysis and experimental investigations, it is found that the contacting resistance of the overlapped yarns in the fabric is the key factor that governs the sensitivity of the fabric sensor. In addition, the fabric structure that determines the structure of the circuit network is also an important factor affecting the characteristics of the fabric sensor.Knitted fabrics are used widely in clothing but being used as sensors for measuring strain and temperature based on their loop configurations are quite novel applications of conductive knitted fabrics [3]. The elastic and extendable substrates of the fabrics make it feasible for these sensors to be used for measuring large tensile strain.The applications of these conductive fabric sensors are based on the changes of the electrical resistance responding to stimuli such as deformation, temperature, humidity, as well as some chemicals. Hence, the resistancestimulus responses are the bases that provide the sensitivity of the fabric sensors. To date, many conductive materials and special fabric sensors have been produced accordingly [1,2,4,8,16]. Several papers have described experimental investigations of the relationships between the load/elongation and electrical resistance of the conductive fabrics [5,9,12]. However, few studies have reported on the mechanism of the conductive fabrics and the key factors of the sensitivity in detail. A theoretical model of electro-mechanical behavior of plain woven fabric made from intrinsically conductive yarn has been proposed, and relationships between the electrical resistance and fabric density, as well as uniaxial tension have been developed [10,18]. In our paper, the electro-mechanical properties of knitted fabrics made from stainless steel multi-filament yarns are investigated both theoretically and experimentally. Theoretical BASIC ASSUMPTIONSThe conductive knitted fabric is treated as a conducting body as the metallic yarn is intrinsically conductive, and the unit length resistance of the yarn is considered

Study of the Contact Resistance of Interlaced Stainless Steel Yarns Embedded in Hybrid Woven Fabrics

“…Related research [7][8][9][10] studied the contacts between electro-conductive yarns embedded in knitted fabrics. Unlike in woven hybrid fabrics, in knitted fabrics, contacts appear between two consecutive conductive loops and not only at the intersection of weft and warp yarns.…”

“…Atalay et al [7] concluded that it is possible to manipulate the sensing properties of knitted sensors and the sensor response may be engineered by varying the production parameters applied to specific designs [8]. Zhang et al [9] created knitted strain sensors by using stainless steel and carbon yarns and identified that the contacting electrical resistance between overlapped fibers is the primary factor in the sensing mechanism. Li et al [10] also modeled the resistance of conductive knitted fabrics by superposition of the length-related resistance and contact resistance and established relationships between the resistance, tensile force, fabric length, and width.…”

Research and Application of the Property of Conductive Knitted Fabrics

“…Good flexibility and stretching property of the knitted fabrics make the sensors to fit measuring the large stretching stress and possess more extensive application range. The fabric texture, loop transfer, contact resistance and loading speed of the conductive knitted fabrics are the factors to impact the resistance of the fabrics & Zhang, 2005. These scholars studied the application of conductive knitted fabrics, and most of them aimed at the plain knitted fabrics, and few of them studied the conductive knitted fabrics with other textures, because other textures such as 1×1 rib texture has different geometric structure and electric property with the plain knitted texture.…”

Investigation of changes in the electrical properties of novel knitted conductive textiles during cyclic loading

“…and the contact resistance ! [5] described according to Ohm's law [6] and Holm's contact theory [7], respectively. Many papers have described theoretical and experimental investigations of the relationship between the resistance and the elongation of conductive fabrics.…”