A NiTi Alloy Weft Knitted Fabric for Smart Firefighting Clothing (original) (raw)
Related papers
Preparation of Shape Memory NiTiNOL Filaments for Smart Textiles
Tekstilec, 2016
A nickel-titanium alloy (NiTiNOL, nitinol) fi lament with a diameter of 200 μm was used for preparing a smart knitted textile fabric with a shape memory eff ect within the range of human body temperatures. The annealing of the fi lament at 500 °C for 30 minutes was followed by air cooling at 20 °C to achieve a suitable transition temperature from martensite to austenite phase within the range between room temperature and 75 °C. The tensile properties of fi laments before annealing and after it were analysed on Instron 6022 dynamometer. The measurements of exact transition temperatures from soft martensite state at room temperature to hard austenite state at heating were made on a dynamic mechanical analysis instrument. From the annealed fi lament a left-right knitted fabric was hand made. The fabric was trained into a selected 3D form by cyclic heating in a strained form at 75 °C for 10 minutes and then cooled at room temperature. For a stable two-way memory eff ect, the nitinol fabric needed to make fi fteen cycles of heating and cooling.
Materials
This study explored the application of shape memory alloy (SMA) springs in a multilayer protective fabric assembly for intelligent insulation that responded to thermal environment changes. Once the SMA spring was actuated, clothing layers were separated, creating an adjustable air gap between the adjacent fabric layers. The impacts of six different SMA arrangement modes and two different spring sizes on thermal protection against either a radiant heat exposure (12 kW/m2) or a hot surface exposure (400 °C) were investigated. The findings showed that the incorporation of SMA springs into the fabric assembly improved the thermal protection, but the extent to which the springs provided thermal protection was dependent on the arrangement mode and spring size. The effectiveness of reinforcing the protective performance using SMA springs depended on the ability of clothing layers to expand an air layer. The regression models were established to quantitatively assess the relationship betwee...
Analysis of hybrid woven fabrics with Shape Memory Alloys wires embedded
Fibres & Textiles in Eastern Europe, 2010
Until recently, Shape Memory Alloys (SMAs) were predominantly developed for applications in the biomedical and engineering industry, and only a limited number of applications in textiles are known. Fabrics made of natural fibres (e.g. cotton, flax and their mixtures) present many advantages, such as wearing comfort, but they are subject to creasing. The aim of this study was to investigate the possibility of compensating for this disadvantage by using SMAs to create aesthetic low crease flax/cotton fabrics. Body Temperature SMAs (BT SMA) that regain their (straight) form when they are subject to human body temperature were used for this purpose. Clothing and bed sheeting are potential applications of these hybrid structures, which become wrinkle-free when they are exposed to the heat of the body, a hair dryer or that generated by an electrical current. The materials selected to achieve this purpose were the following: (1) textile yarns (e.g. single cotton or flax/cotton yarns, two-f...
Thermoresponsive Shape Memory Fibers for Compression Garments
Polymers, 2020
Their highly deformable properties make shape memory polymers (SMP) a promising component for the development of new compression garments. The shape memory effect (SME) can be observed when two polymers are combined. In here, polycaprolactone (PCL) and thermoplastic polyurethane (TPU) were melt spun in different arrangement types (blend, core-sheath, and island-in-sea), whereas the best SME was observed for the blend type. In order to trigger the SME, this yarn was stimulated at a temperature of 50 °C. It showed a strain fixation of 62%, a strain recovery of 99%, and a recovery stress of 2.7 MPa.
Materials Research Express, 2020
The aim of the study was to obtain a smart textile material with shape memory alloys. NiMn-based shape memory alloy was produced by arc melting system for this purpose. Phase transition temperatures of the fabricated alloy were determined by using differential scanning calorimeter (DSC). The crystallographic structure of the fabricated alloy was characterized by x-ray diffractometer (XRD). The fabricated shape memory alloy was converted to the particle form and filled into polymer matrix to obtain shape memory effect of this polymeric composite material. Polymeric composites (PCs) were produced in film form and shape training of PCs were studied under different conditions. The shape memory behavior of samples was investigated into the water for fast response during applying heat. Damping capacity of composites was measured by using dynamic mechanical analyzer (DMA) according to temperature rising. The shape recovery was observed under certain stimuli on the SMA filled polymeric comp...
Journal of Industrial Textiles, 2018
Cushioning pads alleviate the effects of mechanical stress on the human body due to impacts and daily activities. One relevant application for such pads is orthopedic insoles used for diabetic foot to improve energy absorption and reduce stress gradient by using suitable materials and structures. This article considers a novel design that improves the energy absorption capabilities of cushioning pads. Experiments were conducted to evaluate the properties of the designed weft knitted spacer fabrics. Six groups of samples were knitted in which steel, polyamide, and shape memory alloy materials were utilized as spacer monofilament. Stress–strain, energy absorption and efficiency diagrams were obtained following the quasi-static compression tests carried out on the samples. Three investigation groups were adopted to evaluate the effect of the spacer monofilament material, diameter, and slope on energy absorption capacity. It was determined that shape memory alloy monofilament with 0.1 m...
Functional textiles driven by transforming NiTi wires
MATEC web of conferences, 2015
Over last ten years, we have carried out extensive research on the use of thin NiTi wires for advanced functional textiles. In this work we discuss general challenges and opportunities in the design, production and processing of NiTi textiles stemming from the fact that NiTi is martensitically transforming metal. As a case example, application of weft knitting technology to NiTi wires is discussed in detail covering technological aspects related to textile processing, shape setting as well as multiaxial thermomechanical properties of final products. Finally, two weft knitted NiTi textile proof-of-concepts with a promising application potential are presented. First, a textile based actuator with large strokes and low forces characteristics is introduced. Second, 3D textiles with temperature-adaptive cross-section height for applications in technical or protective textiles are described. This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits distribution, and reproduction in any medium, provided the original work is properly cited.
Development of multi-layered weft-knitted fabrics for thermal insulation
Journal of Industrial Textiles, 2019
The main goal of the presented study was to develop new multi-layered weft-knitted structure for thermal insulation and to investigate the dynamic of the heat transfer through this fabric. For knitting of outer and inner layers of this structure, different raw materials of yarns were used, i.e. wool, cotton, polyester and acrylic yarns. All the newly developed multi-layered weft-knitted fabrics show thermal insulation as, after 1 h of observation, temperature on the outer layer of all tested fabrics does not reach 40℃, i.e. the temperature of a heated plate. The results of this research showed that the nature of the yarns has a significant influence on the air permeability and dynamic of the heat exchange through the multi-layered structure, as it influences porosity of the knitted fabric. The results showed that the best fabric was the one where the outer layers are knitted from woollen yarns and the inner layer from polyester filament yarns.
Design and fabrication of Temperature Sensing Fabric
Journal of Industrial Textiles, 2013
A temperature sensing fabric is described, along with the manufacturing techniques required to produce the fabric on a computerised flat-bed knitting machine. Knitted sensing fabrics with copper, nickel and tungsten wire elements have been produced with resistances ranging from 3 to 130 Ω. The most successful samples have been created using textile-wrapped, enamelled wire and not only the textile character of the sensing element was enhanced, but also its tensile strength. A mathematical relationship has been derived between the temperature and resistance of the knitted sensors and this can be used to optimise its dimensions to achieve a targeted reference resistance. The temperature-resistance curves demonstrate a linear trend with a coefficient of determination in the range of 0.99–0.999 and can be integrated into garments to monitor skin temperatures.