Anura Fernando

Thermo-Mechanical Behavior of Textile Heating Fabric Based on Silver Coated Polymeric Yarn

This paper presents a study conducted on the thermo-mechanical properties of knitted structures, the methods of manufacture, effect of contact pressure at the structural binding points, on the degree of heating. The test results also present the level of heating produced as a function of the separation between the supply terminals. The study further investigates the rate of heating and cooling of the knitted structures. The work also presents the decay of heating properties of the yarn due to overheating. Thermal images were taken to study the heat distribution over the surface of the knitted fabric. A tensile tester having constant rate of extension was used to stretch the fabric. The behavior of temperature profile of stretched fabric was observed. A comparison of heat generation by plain, rib and interlock structures was studied. It was observed from the series of experiments that there is a minimum threshold force of contact at binding points of a knitted structure is required to pass the electricity. Once this force is achieved, stretching the fabric does not affect the amount of heat produced.

Continuous objective recording of fetal heart rate and fetal movements could reliably identify fetal compromise, which could reduce stillbirth rates by facilitating timely management.

Stillbirth currently affects approximately 1 in every 200 pregnancies in the United Kingdom. Fetuses may exhibit signs of compromise as part of a stress response before stillbirth, including reduced fetal movements (RFM) and fetal heart rate (FHR) alterations. At present, and despite widespread use, current fetal monitoring is not associated with a reduction in perinatal mortality rate (PMR) as signs of fetal compromise are not adequately detected. This may be attributed to inaccuracies resulting from manual interpretation of results or subjective assessment of fetal activity. In addition, signs of compromise often occur only hours or days before fetal death, so may be missed by current monitoring methods, which are performed intermittently. A significant consideration is that correct identification of these signs and consequent intervention can result in the delivery of a healthy baby, thus preventing stillbirth. A hypothesis is presented, proposing prompt detection of fetal compromise with the use of 24-hour continuous objective fetal monitoring. With focus placed on obtaining long-term FHR and fetal movement data, prior interest has been found in developing devices for this purpose. However, introduction into clinical practice has not been achieved. Investigation of the hypothesis will begin with the design of a device to record the mentioned parameters, followed by an appropriate validation process. Should development and testing be successful, an eventual comparison in PMR with the use of continuous fetal monitoring vs current monitoring would address the hypothesis. It is suggested that a timely yet reliable indication of fetal wellbeing obtained via long-term monitoring would allow prompt and appropriate obstetric intervention and consequently reduce PMR.

The Application of a Piezo-Resistive Cardiorespiratory Sensor System in an Automobile Safety Belt

Respiratory and heart failure are conditions that can occur with little warning and may also be difficult to predict. Therefore continuous monitoring of these bio-signals is advantageous for ensuring human health. The car safety belt is mainly designed to secure the occupants of the vehicle in the event of an accident. In the current research a prototype safety belt is developed, which is used to acquire respiratory and heart signals, under laboratory conditions. The current safety belt is constructed using a copper ink based nonwoven material, which works based on the piezo-resistive effect due to the pressure exerted on the sensor as a result of expansion of the thorax/abdomen area of the body for respiration and due to the principle of ballistocardiography (BCG) in heart signal sensing. In this research, the development of a theoretical model to qualitatively describe the piezo-resistive material is also presented in order to predict the relative change in the resistance of the piezo-resistive material due to the pressure applied.

Scalable Production of Graphene-Based Wearable E-Textiles

Graphene-based wearable e-textiles are considered to be promising due to their advantages over traditional metal-based technology. However, the manufacturing process is complex and currently not suitable for industrial scale application. Here we report a simple, scalable, and cost-effective method of producing graphene-based wearable e-textiles through the chemical reduction of graphene oxide (GO) to make stable reduced graphene oxide (rGO) dispersion which can then be applied to the textile fabric using a simple pad-dry technique. This application method allows the potential manufacture of conductive graphene e-textiles at commercial production rates of ∼150 m/min. The graphene e-textile materials produced are durable and washable with acceptable softness/hand feel. The rGO coating enhanced the tensile strength of cotton fabric and also the flexibility due to the increase in strain% at maximum load. We demonstrate the potential application of these graphene e-textiles for wearable electronics with activity monitoring sensor. This could potentially lead to a multifunctional single graphene e-textile garment that can act both as sensors and flexible heating elements powered by the energy stored in graphene textile supercapacitors.

Study of electro-thermal properties of pyrrole polymerised knitted fabrics

This paper presents the results of research work carried out to investigate the heating properties of nylon knitted fabric impregnated with a polymerised solution of polypyrrole. The inspection of the molecular polypyrrole electro-conductive pathways responsible for the heating effect of the knitted fabric was investigated using a scanning electron microscope. Further to this, the heat generated by the polypyrrole impregnated fabric was observed under varying power supply terminal separation distances in order to understand the relationship between the length of the polypyrrole electro-conductive fabric and the level of heat generated. The sample with the lowest terminal separation distance i.e. 5 × 1 cm2 produced more localized heat and reached a temperature level of 114℃ in less than three minutes. Additionally a thermo-mechanical characterisation of this knitted heating material was carried out against varying levels of strain and compression. The maximum stress and ultimate strain values of both treated and untreated samples were found to be similar. However, it was observed that the extensibility of the samples affected the generation of heat. The suitability of knitted fabric impregnated with polymerised polypyrrole heating elements for in-car applications where the heating elements may be next to skin was also discussed. The investigation concluded that polypyrrole heating fabric is suitable for next-to-body heating applications which can be engineered by controlling the optimum electrical pathways provided by the network of polypyrrole molecular chains together with the correct power supply levels to work under a defined fabric strain range. The purpose of the current research is to provide a new material that could help to develop heating fabrics with improved textile properties.

Piezofilm yarn sensor-integrated knitted fabric for healthcare applications

Continuous measurement of cardio-respiratory signals offers various kinds of information valuable for the diagnosis of disease and management of the disease process. The article reports the development of the Piezofilm yarn sensor for healthcare applications, and investigates its performance by monitoring cardio-respiratory signals of human body over an extended period of time. Piezofilm yarn sensor was developed by embedding the thin PVDF strips within the textile yarn. The working mechanism of the Piezofilm yarn sensor is based on voltage generation due to the applied stress. In order to deploy the Piezofilm yarn sensor in the application environment, it was integrated into the knitted textile fabric and then sewn to form belt to be placed at the chest wall and wrist area. The raw signals were acquired through the Piezofilm lab amplifier, National Instrument data acquisition device and SignalExpress software. Fast Fourier Transform analysis was performed to calculate the average cardio-respiratory signal frequencies. Based on Fast Fourier Transform analysis, an additional signal-processing step was added to eliminate the unwanted mechanical interference and body signals by using an Infinite Impulse Response band pass filter. The Piezofilm yarn sensor embedded sensing fabric was able to measure both respiratory rate and heart beat rate under static and dynamic conditions. The wrist area measurements for heart beat signals were found to be more uniform in comparison to the chest area measurements. Apart from the general healthcare, this sensing fabric could also be used in studies related to biorhythms, sports, detection of sleep apnea and heart problems.

Multifunctional Carbon Fibre Tapes for Automotive Composites

Cabon fibre composites are used where mechanical performance such as strength, stiffness and impact properties at low density is a critical parameter for engineering applications. Carbon fibre flat tape is one material which is traditionally used to manufacture three-dimensional composites in this area. Modifying the carbon fibre tape to incorporate other functions such as stealth, electromagnetic interference, shielding, de-icing, self-repair, energy storage, allows us to create multi-functional carbon fibre tape. Researchers have been developing such material and the technology for their manufacture in order to produce multifunctional carbon fibre based components more economically and efficiently. This paper presents the manufacturing process of a metallised carbon fibre material for a chopped fibre preforming process that uses electromagnets for preforming instead of traditional suction airflow fibre deposition. In addition, the paper further presents mechanical and magneto-static modelling that is carried out to investigate the bending properties of the material produced and its suitability for creating 3D preforms.

Investigation of the Effect of Processing Parameters on 3D Printed Structures

Sandwich panel with lattice core for aircraft anti-ice system made by Selective Laser Melting / Varetti, Sara; Ferro, CARLO GIOVANNI; Casini, ANDREA EMANUELE MARIA; Mazza, Andrea; Maggiore, Paolo; Lombardi, Mariangela. In: INTERNATIONAL JOURNAL OF ADVANCEMENTS IN TECHNOLOGY. ISSN 0976-4860. ELETTRONICO. 9(2018), pp. 73-73. ((Intervento presentato al convegno 2nd International Conference on 3D Printing Technology and Innovations tenutosi a London (UK) nel March 19-20, 2018. Original Sandwich panel with lattice core for aircraft anti-ice system made by Selective Laser MeltingThe advent of additive manufacturing techniques, namely Fused Deposition Modeling (FDM), holds many promising prospects for medical applications, from tailored polypills for personalized medicine to patient-specific implants. However, the lack of pharmaceutically-acceptable materials that possess suitable properties for FDM is the main issue standing in the way of turning FDM into a commercially viable process. And although a number of research efforts has demonstrated the feasibility of using blends of pharmaceutically relevant polymers to print pharmaceutical dosage forms, there remains littleto-no investigation into the critical parameters that govern the feasibility of an FDM process. Mechanical properties of the filament used in FDM is one such critical parameter; part of the filament feeding process involves rotating gears pushing the filament into a pinhole slit that leads on to the heating element of the printer. Trial and error attempts at feeding various inhouse prepared filaments to the printer revealed that filaments need to possess specific mechanical properties; filaments which are too brittle will fracture inside the print head causing a blockage, filaments which are too deformable will coil around the conveyer gears without threading into the melting zone. This presentation outlines an in-house developed method to identify the desired mechanical properties for FDM filament: A TA.XT 2 Texture Analyzer fitted with an in-house prepared rig loosely based on the spaghetti flexure rig was used to quantify forces required to deform a number of commercial and in-house filaments. Principal Component Analysis (PCA) was used to sort the data collected from the texture analysis and categorize the various filaments into feedable and non-feedable. The method was then employed to evaluate the feedability of an ibuprofen formulation to verify its suitability as a method to test the mechanical properties of filaments.W 3D printing technology research accelerating year by year and with increasing number of applications of adaptive manufacturing in final products, engineers face the problem of having access to realiable design codes for elements manufactured with those new technologies. By the very nature of the 3D printing technology, manufactured elements are characterized by high degree of anisotropy of strength properties. The aim of the presented research is to establish reliable testing protocol for assesment of anisotropy of mechanical behaviour and to create data bases of experimental results for validation and calibration of numerical models. Besides traditional experimental techniques, new techniques based on Digtal Image Correlation (DIC) and in house developed software are incorporated into the experimental pipeline. In the presented research relatively, simple test cases of specimens under uniaxial tension and compression were analyzed. That allowed for simpler correlation of results from strength testing machine, DIC analysis and simple mechanical model, as well as clearly showed anisotropy effects. The rough surface of printed specimens turned out to be ideal for DIC measurements. The results obtained can be used to calibrate numerical models before testing more complex cases.This conference abstract is published by OMICS International under the Creative Commons Attribution 4.0 International Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/

Textile technologies for the manufacture of three-dimensional textile preforms

Purpose This paper aims to provide an overview of the current manufacturing methods for three-dimensional textile preforms while providing experimental data on the emerging techniques of combining yarn interlocking with yarn interlooping. Design/methodology/approach The paper describes the key textile technologies used for composite manufacture: braiding, weaving and knitting. The various textile preforming methods are suited to different applications; their capabilities and end performance characteristics are analysed. Findings Such preforms are used in composites in a wide range of industries, from aerospace to medical and automotive to civil engineering. The paper highlights how the use of knitting technology for preform manufacture has gained wider acceptance due to its flexibility in design and shaping capabilities. The tensile properties of glass fibre knit structures containing inlay yarns interlocked between knitted loops are given, highlighting the importance of reinforcement yarns. Originality/value The future trends of reinforcement yarns in knitted structures for improved tensile properties are discussed, with initial experimental data.