Narrow and Smart Textiles

Since the arrival of electronics in the textile field, the ribbon transformed into e-ribbon inaugurates its functionalities with two unseen features in hand: it joins together physically and electronically different worlds, arriving to the transformation of itself into an electronical component, in other words, materializing the service. The e-garments, as well as e-ribbons, intimately ally esthetics with utility. Halfway between product design and fashion, it is obliged to integrate the end user’s opinion and think about new services to offer to the digital world. Going from connectivity through clients support and new marketing strategies, E-ribbons are getting their way in shaking the secular habits of a dynamic field, and yet, a linear one. The narrow textiles have a pioneer and strategic role to play NOW.

For the treatment of dermatologic diseases such as actinic keratosis with photodynamic therapy (PDT), a light emitting fabric (LEF) is developed. The light emission of the LEF should be as homogenous as possible to assure a successful and pain-reduced treatment. The considered LEFs are tapes, that are woven with polymer optical fibres (POFs). The light emission varies for different weaves. A prediction of the light emission by modelling and simulation is expected to give insight in the processes and help with the investigation of finding a tape with the most homogenous light emission. In this paper, a modelling procedure is presented, with which the light emission can be regarded based especially on the weave type and setting. The modelling procedure incorporates weaving simulations as well as ray tracing simulations. To discuss the importance of weave settings on the light emission, tapes that are woven with different warp tensions are regarded. The applicability of the modelling procedure to predict light emission of complete weaves is shown.

The purpose of this study is to analyse the influence of weaving parameters of 3D warp interlock fabrics on their mechanical properties. Using the same yarns in the warp and weft direction, four main product and process parameters have been chosen as the weave diagram, the weft density and positions of stuffer and linking warp yarns inside the woven structure. Based on several 3D warp interlock architecture produced on the same dobby loom, the mechanical characterization of these fabrics have been performed by unidirectional tensile and bending tests, both in the warp and weft directions. Thanks to this complete protocol; a comparison between 3D warp interlock woven architectures has been done to reveal the influence of process and product parameters on their mechanical performances.

Textile materials and their modifications for use in bio-based fiber reinforced materials are presented. Main results are related to hydrophobic and antimicrobial functionalization, to make the natural fiber materials more suitable for application in composite materials. To realize a fully bio-based composite, it is the challenge to evaluated also bio-based finishing agents offering the wished properties.

Weft-knitted structures are very suitable for draping of different 3D forms because of their flexibility and the possibility to change the sizes of the different loops redistributing the yarn lengths at the different loops. The FEM analysis of such 3D forms requires the knowledge of the elastic behaviour and particularly the elasticity modulus and Poisson’s numbers of the single cell at the different regions of the structure after the deformation. This work presents a method for numerical prediction of these values and experimental validations. The numerical prediction is based on several steps. First, the 3D geometry of the loop is generated based on a geometrical model for the loops. This geometry is then used, together with the properties of the yarns (wires) and the matrix for homogenisation calculations. The geometrical model is implemented into C++ Software tool within the TexMind suite, which exports it into WiseTex-XML format. This is then used within the TexComp software for homogenisation, where the method of inclusions is used to then compare the results with the experimental ones.

The intention of this paper is to give a short overview of the results of the doctoral thesis of Dr.-Ing. Andreas Kretschmer. The scope of the work includes among others two predominant parameters of the braiding process with major influence on the rope’s bending properties. Furthermore, a newly designed braiding machine is introduced.

The following study deals with the main interlacement variations and possibilities of the new covering technology D-3F. There are well-known processing technologies for the covering of extruded hoses or other tubular cores in order to increase their radial stiffness, like braiding or spiraling. The main disadvantage of the spiraling layers is the limitation in stability of the single windings, caused by missing interlacements. An advantage might be the fiber deflections and the resulting directed mechanical properties in combination with the achieved productivity. On the other hand, it is impossible to cover cores with changing diameters and resulting local angles higher than the friction angle of the current materials. These forming cores or profiles are often covered by the more suitable braiding technology. Braided structures can be produced stably based on proper interlacement between the two or three thread systems inside. In fact, the braiding technology has its limitations concerning the productivity. The interlacement of the thread, which stabilizes the structure from one side, is the reason for broken filaments as a result of the deflection of the threads from the other side. The number of broken filaments is proportionally increasing with the speed of the braiding process. In order to combine the advantages of both spiraling and braiding into a new productive and fiber-friendly technology, a new machine concept was developed and patented. The new weaving-like binding structure “D-3FG” (“Denninger-3Faden Geflecht”) combines the properties of two layers and weaving-like interlacements.

This works presents a numerical investigation about the production and simulation of braided products with complex cross section. The geometrical modelling of tubular and flat braids is already well described in the literature and implemented in several scripts and commercial software like TexMind Braider. In the literature are reported as well several works about the modelling of 3D braided structures, created using different 3D braiding techniques. For the case of complex maypole braiding machine with horn gears are reported some works with the software TexMind Braiding Machine Configurator, which emulates the carrier motion for the creation of the 3D geometry of the braids. This work presents evaluation of the possibilities of the software for designing machines with large number of horn gears in custom arrangements and at the same time presents the results of a large set of tests of the possible combinations for arrangements of horn gears with different size for the production of complex multilayer braided structures like T-, and double-T-profiles. The investigation shows, that the possibilities for carrier arrangement are directly connected with the topology of the tracks of these carriers and for structures with multiple tracks more empty places in the arrangement is required. For the cases, where for such structures suitable machine configuration and carrier arrangement is found, an simplistic 3D geometry of the braid is generated and can be used for FEM calculations, relaxation and other computations of the properties.

In this paper, the relationship among primary helix, secondary helix and braiding curve is discussed and it concludes that the braiding curve is the projection of secondary helix on the braiding surface. Based on this conclusion, the equation of braiding curve is derived using Frenet frame. The geometrical models of braided strands are realized by two methods, one is based on the mathematical models; the braiding curves are obtained by their equations directly. The other is based on the projective relationship using SolidWorks™. A projective surface has been built and employed to realize the projection of secondary helix on the helical surface, the braiding curve is obtained by the intersection of projective surface and the helical surface. For both methods, the strands are built by sweeping the cross section along the braiding curve. The modeling methods introduced are not confined by the braiding angle and cross section of strand and could be used to simulate different braided structures.

Braided polymeric biomedical stents were developed as an alternative to replace commercial metallic ones presenting several failures caused especially by the used metals. Among those materials, the polyethylene terephthalate PET has been used to develop stents since it is suitable for several biomedical uses, such as vascular prosthesis. But in order to obtain the ideal PET-braided stent, its manufacturing parameters should be carefully chosen. For that, the current study aims at developing polymeric braided vascular stents made of PET monofilaments. According to a two-level fractional factorial design, stents are braided by varying most of their manufacturing and heat-setting parameters (monofilament diameter, stent diameter, braiding angle, heat-setting temperature and heat-setting time). Then, the structural (cover factor, porosity, unchanged bending diameter) and mechanical tests (radial compression, longitudinal compression, longitudinal elongation) are performed. Developed stents performances are compared to those of the Gore’s Nitinol stents. Then, effects of manufacturing parameters on stents properties were investigated. After selecting the significant parameters for each performance, optimal values were determined. According to the experimental results, manufactured stents showed good performances comparing to Nitinol stents. According to the factorial analysis, considered factors have different effects from a response to another. The most common significant factors are monofilament diameter, stent diameter and braiding angle, whereas the least important factors are heat-setting temperature and heat-setting time. Also, models are adequate (p-value < 0,05 and R² > 80%) at the 95% confidence level. Furthermore, the obtained optimum stent’s manufacturing settings can lead to PET-braided stents as performant as Gore’s Nitinol ones.

Triaxial braided reinforcements are extensively used as main constituent materials in various biomedical and composite applications. The material parameters, and the choice of process parameters during the braiding process, have a significant influence on the geometrical and mechanical properties of these reinforcements. In this study, the manufacturing on a braiding loom of triaxial braids with a large range of braiding angle is presented. On these samples geometrical properties, as bias yarn length, crimp, linear mass, are experimentally identified in function of the braiding angle. From uniaxial tests, the specific tensile behavior of these braided fabrics is characterized. These results are compared with analytical models described in the literature. Associated to this experimental approach, the geometry of these triaxial braids is numerically modeled thanks to TexMind Braider software dedicated for three-dimensional creation of braided structures. Comparison between characteristics experimentally identified and computed is analyzed.

A concept of a rope-driven handling device was developed. The scope of the work was to achieve a significant noise reduction by the utilisation of high-performance fibre ropes actuated by motor winch devices. A two-dimensional demonstrational was implemented and analysed. Furthermore, a concept for the compensation of the weak axis was set up. In comparison to conventionally built axles, a significant lowering of the emitted sound pressure level was achieved.

This paper presents an overview about the patterning possibilities of the new variational braider of the company Herzog GmbH. Presented are two practical examples with the sequences of their programing and some issues about the programming with the user interface. Some configurations for production of flat braids are checked using simulation software TexMind Braiding Machine Configurator. It is found that regular flat braids with three carriers and irregular flat braids with four carriers can be produced with the machine as well.

Conveyor-technical and winch-based applications like elements in cranes or shipbuilding with required payloads of 5 tons and above put enormous requests on high-strength fibre ropes. The application of wear-reducing coatings is therefore essential. In case of the structural design of fibre ropes with large diameters, a complete penetration with coatings is not achievable with conventional coating techniques. Therefore, the coating with the help of ultrasonic is a new way to improve the penetration of fibre ropes with higher diameters.

Polyarylate fibers are commonly used in rope making, in lightweight structures, textile reinforced composites, and textile-based mechanical components for technical applications. Due to higher demands on abrasion resistance of fiber ropes in technical applications, such as hoisting and lifting applications, investigations have been carried out to improve the abrasion resistance of braided fiber ropes, made from polyarylate fibers Vectran™. Overlay finishes and coatings have been applied on braided fiber ropes to investigate the influence of fiber finishes and to investigate the influence of coatings and overlay finishes on the ropes’ properties. Further, in a part of the rope samples, the fiber finish has been removed before coating, in order to investigate the interactions between fiber finish and applied coatings.

Based on the results of a research project it is described how material selection and user friendly design improves the properties of metal-textile hybrid carrier modules, in comparison to conventional carriers, and thus generate new marketing approaches. By textile means processed nets and straps with metal reinforcement structures form the starting point for these new variants of carrier constructions. The textile inner layer has integrated sensors and application-oriented coating. To prevent harmful environmental influences on the structure of the textile construction, an additional outer layer can be installed. For the textile sensors, it was necessary to capture the current state of the art, to transfer a preferred version in a practical application.

Additive manufacturing combined with highly elastic, extensible textile materials provides the opportunity to explore a new range of materials: 4D textiles. The name is derived from “4D Printing”, a combination of 3D printing and a time change element, providing the fourth dimension. In the case of 4D textiles, the time response is necessary, but also the textile material provides a crucial role in responding to external stimuli. Whereas 4D printing is currently limited to very small deformations and very slow changes in time, 4D textiles offer the opportunity to increase deformation and response time. This paper covers the concepts of 4D printing, achievements in 3D printing, and the concept of 4D textiles. The role of materials, critical process parameters, critical textile processes, and potential application areas are presented. Strengths and weaknesses of 4D textiles are discussed.

Nanofiber mats from different polymers, possibly blended with other organic or inorganic components, can be created by the electrospinning technology. Such nanofiber mats possess large surface–volume ratios in comparison with other textile fabrics, such as common nonwovens. This property enables enhanced interactions with their environment, making them suitable for applications in wound dressing, drug delivery, biotechnological filter technology, etc., especially if prepared from biopolymers with intrinsically antimicrobial or other qualities. In a recent project, we investigate the possibilities to create such nanofiber mats from diverse (bio-) polymers by “green” electrospinning, i.e., electrospinning from aqueous solutions or other nontoxic solvents. The article gives an overview of the latest results from needleless electrospinning pure polymers and polymer blends as well as typical physical and chemical properties of the created nanofiber mats, especially for medical and biotechnological purposes, and shows diverse possibilities to crosslink water-soluble biopolymer nanofiber mats.

Sensorizing of woven tapes is the starting point for many innovations when physical properties like force, pressure, temperature, shape change, or moisture have to be supervised in medical textiles, wellness requisites, load bearing belts, buildings, and sporting goods. In order to produce textile-based sensors, fibers or bundles of fibers, ribbons and other textile substrates are furnished with coatings which can advantageously be tailored to any desired sensing capability. Hereby, the textile material remains nearly unchanged and keeps up its textile typical behavior. The sensorized area is free from nontextile components. The presented chapter deals with textile sensors for the measurement of contact pressure, temperature, and moisture. For this reason, sensorized threads are interwoven into tapes and connected with wires for the transmission of signals. Further on, woven tapes with sensing coatings and their applications are presented. A second part of this chapter is dedicated to questions regarding the accessibility to evaluation units, the minimization of cross-sensitivities and environmental influences as well as the reproducibility of sensor characteristics. Finally, a testing method for smart textiles is introduced based on simultaneously applying mechanical stress and monitoring the change in electrical resistance.

Wearables and smart textiles are a growing field in the fashion trade. Primarily, the textile industry can thereby expand and become again more local in Germany. The interest in clothes and textiles with new functions rises continuously, resulting in the fact that functionality and design should be well joined to convince the end-consumer. In an interdisciplinary project of designers and engineers, a flexible solar module was integrated into clothes that it is not visible at first sight. It was hidden behind a laser-cut to provide a good integration of technology in clothes and to enrich the design. The influence of the laser-cut was analyzed in various measurements and was optimized so that the solar cells can still provide enough power to control a sound module for MP3 files. With textile buttons, which contain conductive textiles and threads, it is possible to operate the music. The results are two androgynous outfits with electronic components. The intention was to develop garments for both genders, to give them a function for increasing the value and to put forward the sustainability.

In the area of medical textiles, several applications necessitate conductive sensors, such as ECG or pulse measurements, breathing sensors, etc. Additionally, connections between electronic elements, data transfer units, and other parts of sensor networks need conductive paths. The resistance of conductive yarns or coatings against mechanical and chemical influences, however, is often low. Silver particles in coatings or on yarns, e.g., can oxidize during washing. Thin coatings can easily be abraded and offer only a low conductivity due to low layer height, while thicker coatings can be stiff and break during bending. In a recent project, we evaluate different coatings with respect to their resistance against mechanical stress due to abrasion against diverse materials, as a typical demand of sensory shirts or other medical textiles. Conductive silicone rubber, as well as graphite-polyurethane dispersions with different graphite concentrations, were coated on diverse textile fabrics in a defined height. Abrasion tests were performed on these samples using a linear abrasion tester. The electrical resistance of the conductive coatings was measured after each test cycle. Additionally, confocal laser scanning microscopy was used to detect micro-cracks or modifications of the coating surface. The article gives an overview of the results and depicts the advantages and challenges of the conductive coatings under examination.

Niche products like smart textiles and other technical high-end products require resource-efficient processes and small batches contrary to conventional textile processes that require larger batches and are water-, chemical- and energy-intensive. This study focuses on digital inkjet printing and UV light curing as a flexible and resource-efficient and therewith economic production process of a smart textile UV sensor. The UV sensor is based on a UV-curable inkjet ink and a commercial photochromic dye. The inkjet ink is cured via free radical polymerization initiated by a UV–LED lamp. This system contains two photoactive compounds for which UV light both cures and activates the prints. An important challenge is therefore polymer crosslinking of the resin and UV-sensing performance of the photochromic dye. In this paper, we present performance as a function of belt speed and lamp intensity during curing. Via wash tests, we investigate the durability of the photochromic prints. The UV-sensing textile is characterized by colour measurements, differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA).

Smart textiles are a rapidly expanding field in the world of textiles, announcing a new and intriguing era. Different functionalities can be added to the textile to make the textile smart and intelligent. One of these functionalities is the addition of light-emitting layers or devices that can be incorporated into the textiles. These light-emitting textiles find a broad application in the field of interior and exterior design and wearable applications. Depending on the application, two light-emitting devices, the alternating current powder electroluminescent (ACPEL) device and the organic light emitting diode (OLED), both consisting out of a stack of thin layers, can be directly printed on top of the textile substrates. With its relatively high AC voltage of 50–200 V, the ACPEL device is more suited for interior and exterior applications while the OLED with a low DC voltage of 3–5 V is a perfect candidate for wearable applications. To maintain typical textile properties such as flexibility, breathability and drapability, different smart designs of the ACPEL devices are suggested, screen printed and analysed. More challenging is to apply the OLEDs on textile substrates. The very thin nanometre range layers make a planarizing layer to smoothen the textile surface indispensable. Different techniques such as spin coating, ultrasonic spray coating, inkjet printing and thermal evaporation are used to apply the complete OLED stack.