Abdelfattah M. Seyam

Woven Fabric-Based Electrical Circuits Part II: Yarn and Fabric Structures to Reduce Crosstalk Noise in Woven Fabric-Based Circuits

One important problem in electronic textiles is crosstalk and lack of signal integrity between conductive lines. Two significant advantages of electronic textiles over tradi tional circuit boards are flexibility and the ability to scale to large areas. Capacitive and inductive crosstalk is aggravated by long parallel conductors, and varies as the electronic textile is flexed into different configurations. This paper evaluates crosstalk between woven parallel conductors. Two new thread structures—coaxial and twisted pair copper threads—to minimize cross talk are developed and evaluated. Significant reductions in crosstalk are obtained with the coaxial and twisted pair thread structures when compared with bare copper threads or insulated conductive threads.

Mechanics of Woven Fabrics Part IV: Critical Review of Fabric Degree of Tightness and Its Applications

Extensive coverage of previous work in the area of developing a dimensionless number or index to express a woven fabrics degree of tightness or firmness is critically reviewed. The review also includes applications of fabric tightness to designs of similar cloth, to weaving resistance, and to their relationships with fabric properties. A new tightness factor, based on a combination of Ashenhursts ends-plus-intersections theory and Loves racetrack geometry, is suggested. The advantages and limitation of the new tightness are discussed.

A Generalized Model for Predicting Load-Extension Properties of Woven Fabrics

A method to predict the load-extension behavior of woven fabrics is proposed. Kawabata et al.s finite deformation theory, which predicts load-extension properties of plain weave and 2/2 twill fabrics in terms of fabric construction parameters and yarn tensile properties, is the basis for the study. The model is generalized to predict the load-elongation behavior of any weave by introducing a parameter that characterizes the interlacing point distribution pattern of the weave. Using the biaxial and uniaxial strain modes, the load-deformation curves over an entire range of strains can be generated. The model applies to woven structures of different degrees of openness, of which the fabric jamming condition is an extreme case.

Mechanics of Woven Fabrics Part III: Critical Review of Weavability Limit Studies

Extensive coverage of previous work in the area of weavability limit theories, their experimental validation, and their practical importance is reviewed. The review also includes previous work on maximum construction relationships derived empirically, as well as a comparison of different theories and empirical studies.

Mechanics of Woven Fabrics, Part I : Theoretical Investigation of Weavability Limit of Yarns with Thickness Variation

Theoretical maximum weavability relationships of fabrics woven from regular warp ends and variable thickness filling yarns are derived by developing a local geometry where the thick filling place is interlaced with warp ends and where warp yarn is interlaced with thick and thin filling yarns. Geometric relationships are derived from the local geometry, and hence a local weavability limit relationship is deduced. The average warp and filling spacings are calculated by developing an imaginary proba bilistic model of a time scale and relating the geometric parameters at different locations. The final expressions for the weavability limit, which represent the fabric sheet as a whole, relate the average maximum warp and filling cover factors to the ratio of average filling yarn to warp yarn diameters; the ratio of thick place of filling to warp yarn diameters; and the ratio of thick place length of filling to the wave length, warp and average filling densities, thick and thin places of filling yarn densities, number of filling yarns in the pattern repeat, and weave design.

Modeling and Simulation for Control in Carding

The purpose of this work is to further study the transfer function model for carding introduced in a previous paper. Our goal is to develop mathematical and computational tools that will ultimately lead to the design of real-time controllers for carding. In this paper, we discuss a linear, time-variant version of the model presented for one carding group. We also present a reduced order, linear model and use it to build a linear estimator (observer) as part of a full-state feedback controller design. Computer sim ulations and experimental results are shown.

Mechanics of Woven Fabrics Part II: Experimental Study of Weavability Limit of Yams with Thickness Variation

A wide range of tightly woven fabrics made from regular thickness warp ends and filling yams with pulse train irregularities was produced to test the validity of the theoretical weavability limit relationships developed in Part I of this study. The in vestigation includes periodic and random thickness variation filling yarns. The results show that the agreement between the theoretical and loom maximum fabric cover factors is fairly good up to eight-harness weaves.

Devices for measuring electrostatic generation and dissipation on the surfaces of polymeric materials

Dynamic electrostatic generation and dissipation on polymer surfaces are of great importance for materials such as yarns and films. To support fundamental research in this area, innovative devices and experimental techniques that can lead to a better understanding of these phenomena are of obvious academic and industrial interest. This paper reports the development of devices for testing the electrostatic generation/dissipation properties of polymer surfaces. These devices include a tester for assessing moving yarns, a high-resistance system to measure the yarns linear resistance, a tester for evaluating stationary fabrics or films while rubbing against a moving surface and a contact charge tester for investigating charge generated by contacting of two surfaces. These devices enable the study of the influences of relative moving speed, yarn tension, electrostatic charge properties of yarns, as well as contact pressure, rubbing speed, number of rubbings or contacts on the static charge properties of films.

Development of Woven Fabric-based Electrical Circuits

This paper describes the development of woven electrical circuits, which are formed by interlacing conducting and non-conducting threads into a woven fabric. Conductive threads in these electrical networks are arranged and woven such that they follow desired electrical circuit designs. Electronic devices can be attached to these electrical networks, which can serve as flexible circuit boards. In these woven circuits, an efficient transfer of current from one conductive yarn to an orthogonal one is achieved by the formation of an effective electrical interconnect at the point of intersection of these yarns. Formation of woven conductive networks also involves disconnect formation or cutting of conductive yarns at certain specified points. Different methods and processes were identified and applied in order to form interconnects and disconnects at specified points of these fabrics. Efficacy of these interconnects was evaluated by DC resistance and AC Signal measurements. The results of these evaluations are reported. The conductive threads woven into these fabric-based circuits were also evaluated for signal integrity issues.

Electrotextiles - Present and Future

Electrotextiles have attracted increasing attention in recent years. The combinations of textile structures that are lightweight, flexible, conformable, and strong, with electronics have aroused keen interest from many disciplines. With technological innovations appearing in both textile and electronics, integration of these has started giving benefits. Innovations like the sensate liner, soft switches and smart composites have found many applications in sports, healthcare, military, aerospace engineering, civil engineering and many other fields. The purpose of this paper is to provide an overview of various electrotextile products available and explain their functionality. Additionally, the paper provides a review of future electrotextile products, which are in the developmental phase, and the challenges that need to be addressed by researchers and industry.